Over the summer months, I’ve been trying out several ball machines in pursuit of finding the best tennis ball machine on the market right now.
There are more reviews to come, but the machine in focus today is the Slinger Bag from Connexa Sports.
The Slinger burst onto the market a few years ago via a successful Kickstarter crowdfunding campaign and has since forged a partnership with Dunlop after being incorporated into the larger Connexa Sports Group.
The product has been well marketed and is one of the more popular ball machines out there, thanks to its accessible price point and portability compared to some heavier machines.
I’ve been testing the Slinger bag for several weeks, so is it any good? How does it compare to more expensive machines? Find out in this full playtest and review.
The Slinger Tennis Ball Machine
The Slinger Bag has a unique luggage-like design, and alongside the ball machine firing section, it has storage for around 144 tennis balls directly above it.
At the rear of the bag, there is a top loading racket compartment section that holds three rackets and then several accessory compartments on the sides to store the charger, the remote key fob, the phone holder and other bits and pieces.
The telescopic ball collector that holds 20 balls when extended is strapped to the side, and at the rear of the Slinger are two wheels with a telescopic handle for wheeling it around.
The oscillator accessory comes in a separate bag, which you can slot over the telescopic handle for carrying around.
In terms of design, I think it is very slick looking, and it draws plenty of attention from people; while most people have guessed it is something sport-related, nobody outside the tennis world that I’ve run into knew it was a tennis ball machine.
The model I have is the Grand Slam pack which includes:
Slinger Bag Grand Slam Pack
- Slinger Launcher
- Remote Control
- Ball Tube (holds 20 balls)
- Camera Holder
Slinger Bag Specification
- Weight: 33lbs/15kg (not including balls)
- Dimensions: 14″ x 18″ x 34″ (35.6cm x 45.7cm x 86.4cm)
- Launch speed: 10-45 mph (16-73 km/h)
- Battery: Lithium lasts 3.5 hours
- Controls: Feed rate and speed knobs on the machine, remote control for on/off and oscillation
- Launch Angle controlled via Elevation Knob 10 and 40 degrees
- Variable ball feed frequency of between 2 and 7 seconds.
- Holds ~144 balls
Setting Up the Slinger Bag
Setting up the Slinger is straightforward. First, ensure it is fully charged by plugging the charging adapter into the port and letting it run before play.
It is also possible to remove the battery and charge that directly if you’d rather leave the bag in the car or in a place where there is no wall socket within reach.
Once you arrive at the court, you unzip the front bottom pocket and fasten it with the carabiner clip, so it stays fully open.
Turning on the Slinger bag is done via a rocker switch, and you then have two knobs to control the speed and the feed rate. There are four lights to indicate battery level.
If you have never used a ball machine before, don’t be alarmed by the tennis ball fuzz, this happens on all ball machines and is never-ending.
You can vacuum it off periodically, which I recommend, but it will be back immediately as soon as you use it again.
There is a side pocket that you open to access the elevation knob, which dictates the angle the ball fires out at from zero to 40 degrees. You loosen it to adjust, then tighten it when happy with the angle.
You then open the top front compartment, which is the ball holder; opening allows the balls to be shuffled around in a larger space.
If you are using the machine for the first time, I’d recommend keeping it off the oscillator, as you will want to play around with court locations first.
To use the oscillator, you place the bag onto the oscillator base, so the wheels are in the grooves, then connect it via the white cable, which locks on magnetically to the control panel. You can then switch it on from the remote control keyfob.
You are ready to go from there, but don’t pick up your racket and sprint to the baseline like Nadal.
I’d recommend using the fob to switch to the machine to ‘go’ while you are standing next to it; then, you can see where the first couple of balls land.
Depending on the speed and bounce location, you might need to adjust.
For first-time use and warm-up, I’d recommend placing the machine behind the ‘T’ of the service boxes, setting the speed to just under halfway, and the angle at around 15 degrees. This provides a comfortable ball to get into the groove.
Before using the Slinger Bag, I’d used a Siboasi ball machine for six weeks; that model is a more traditional style ball machine with many features.
So my preconceptions of the Slinger would be that it’s not as good, given its three times cheaper and doesn’t have as many options.
However, my first time using the Slinger impressed me. While it is not as good in some areas as the Siboasi, it’s better in others which I’ll get into below in the playtest section.
The first impression I liked was how easy the bag was to move around. It is easy to tilt to get onto the wheels, and you could quite easily walk a fair distance to the courts if you needed to; bringing it on public transport would also be no problem.
While stairs and rough surfaces like gravel aren’t going to be easy to traverse, it’s easy enough to lift and carry for a brief period if you need to.
I’ve carried it up and down three flights of stairs several times, and while it’s cumbersome, it is light enough to be manageable for most people. As you can see, it fits in a car boot comfortably. Mid-size SUV below for reference.
I particularly like the wheels on the Slinger; they’re slimline but substantial and have a rubber feel. They run super smoothly, too, and they feel like the wheels you get on a well-made suitcase.
This is compared to the Siboasi machine, which has fully plastic thick chunky wheels, which are a bit clunky.
If they added a rubber coating to them like the Slinger’s, wheeling around would be much smoother, especially on pavements.
I also liked how the Slinger is one complete package; with other ball machines, you need the machine, ball baskets and your rackets which can involve a couple of trips back to the car to get everything, whereas the Slinger has everything within the bag.
Slinger Bag Playtest
The Slinger comes with a cardboard placard, suggesting where to position the machine and what settings to use.
I think the ball boy suggestion is pointless, as it’s firing you one ball you catch then serve with. Practising serves with a basket is far easier, and when do club players ever have a ball boy to chuck them a ball? 😁
My first try of the Slinger was indoors, and I set it just behind the service line at the following speed and feed settings.
After my first few hits, I was surprised at how much top spin the Slinger generates.
I thought the ball might feel lacklustre given it doesn’t have the speed capability of bigger machines, but it produces an exceptionally challenging ball with a penetrating topspin.
It does this because it only has one wheel, whereas other machines use two wheels that run at different speeds, producing a flat ball, topspin and underspin.
I’ve seen some other comments that only having topspin is a drawback of the Slinger, but I don’t think this is a problem.
I think it is an advantage because as your game progresses, especially if you’re a junior, you will run into more and more topspin.
I remember when I first played someone who hit the ball with massive topspin off both wings; it was like nothing I’d ever seen before, and the reaction off my stringbed was so alien to me that it took several games to adjust to.
The Slinger produces that type of ball, and it is the type you want to face as it challenges you and will make you a better player.
You are lucky to find more than 2 or 3 players at a tennis club that can hit that type of spin, so having a machine that can fire out ~140 heavy spin balls at you is highly advantageous.
If you can start dealing with high bouncing balls penetrating the court, you’ll also get better at mopping powder puff moon balls from the dreaded ‘pusher’ that everyone at every level of tennis has lost to at some point.
On my first session, I hit an entire bag of balls on that setting, then moved the Slinger Bag back to the baseline, increasing the speed to the max while keeping the angle the same. The result was more of the same with a shoulder-high bouncing ball which gives a real workout as you’re using smaller muscle groups.
I then put the oscillator on, which makes things even more challenging as you’re now hitting high balls on the run, which is extremely tiring if you do a whole basket of them.
For the second session, I decided to try more targeted drills, so this time I set up the bag on the same side of the net as myself and put the speed near its lowest and the angle near 40 degrees.
This produces a type of hand-fed ball, and I wanted to practice stepping into the court and getting low to hit short forehands, retreating to the middle behind the baseline and repeating.
This type of drill helps develop the short steps required for better footwork. See the video below for the kind of thing I’m talking about; replace Coach Nick with the Slinger and you have a similar drill:
To close the session, I decided to test out the Slinger on one of the least practised shots in tennis – the overhead.
For this, I set the bag inside the baseline on the centre service line with a speed near max and an angle of 40 degrees. This fires up lobs at a decent height, and you can also practice back pedalling if you stand close to the net, which is challenging.
When writing this review, I’ve used the Slinger Bag for around fifteen 90-minute sessions, and I’ve been very happy with its performance.
Initially, I thought I’d be swapping between the Slinger and the Siboasi I was using, but I kept the Slinger in the car for five consecutive sessions, so I didn’t miss the extra features and preferred the lighter portability aspect of the Slinger.
What Can You Practice with the Slinger Bag?
Despite not having some of the features of other ball machines, you can practice every type of shot in the game with some creative court placement. So far, I’ve used the Slinger to practice:
- Groundstokes (duh)
- Half Volleys
- Drive Volleys
- Moon Balls
- Cross court drills
- Footwork drills
Even when the battery conked out on me halfway through a session, all was not lost as you can stick the bag next to you and practice serves without needing to constantly bend over and pick up balls from the ground.
For many drills, you don’t even need to move the bag; for example, I put the bag in one of the corners, a couple of feet inside the baseline and just inside the sideline, which fires the ball cross-court into my forehand.
I then hit several cross-court forehands, go down the line for a couple, back to cross-court, and then come in and hit a few volleys. You can then backpedal to try to get the next ball for some more cross-court groundstroke hitting.
Recommended Slinger Bag Drills and Settings
|Lob / Drive Volley / High Volley
|Centre, just inside the baseline
|Mid Court High Forehand
|Centre, behind service T
|Cross Court Groundstokres
|Inside Sideline, 2 feet from the service line
|Hand Fed Type Ball
|Your side of the net
Got any drill suggestions with their associated settings? Let me know in the comments.
For other drill ideas, there are several Youtube videos you can watch, the Tennis Mentor has a whole series on using the Slinger for all levels of play, and there are other drill videos from Hammer It Tennis which are worth checking out.
Finally, there are quite a few coaches that offer stroke analysis if you send them the footage, so Slinger is also useful for videoing a practice session to send them.
It’s not always easy to find a hitting partner who can hit consistently, so if you can film yourself hitting 50 forehands in a row off a similar ball, this will be helpful for a coach.
Why I Like The Slinger Bag
The thing I like most about the Slinger Bag is that it’s a solid all-rounder. It doesn’t have all the bells and whistles of other ball machines, but for sub $1000 / £1000, it more than competes with them.
Whereas my more expensive ball machine sits in the middle of the court and can do everything from one location, once you start playing around with the placement of the Slinger Bag and the speed/launch angle, you can recreate most of the things more expensive machines can do.
The other big plus point was how much top spin the Slinger bag generates. At the recreational level, everyone loves that waist-high ball, which means shoulder-high balls are under-practised if not actively avoided.
The Slinger forces you to play those types of balls, and you will become a better player from it.
Look at how the pros on the ATP tour destroy those shoulder-high mid-court balls, and they’ve done that through repetition, which a ball machine can help you do too.
Finally, I like the all-in-one nature of the bag. Everything you need for a session is stored in the bag: racket, balls, ball collector, ball machine, remote control.
You turn up to a court, wheel it on, and after a couple of minutes of setup, you are ready to start hitting (don’t forget to warm up!)
Are There Any Drawbacks?
The first minor drawback I discovered was that not all the balls would find their way into the rotating section before falling into the rotating hopper.
This is because there is a lip around the edge where the balls get stuck, and typically I get anywhere from 3 to 10 balls that don’t fall in.
It’s an easy enough fix by placing something behind the velcro mesh in the bag – I used air-filled sacks used for packaging that you often get in Amazon boxes when it’s oversized compared to the item you ordered. You could also use foam.
Please note: The issue of balls not falling into the hopper has been addressed in the 3.0 version of the Slinger Bag.
My bag is not the latest version, and the newer one, which you’ll receive if you order the bag in the USA or UK today, has a different internal setup, and some carry handles that help gets the bag into the car etc.
I believe some areas will still be selling the 2.0 version if they have stock. So if having the latest version is crucial for you, ask before ordering.
Another drawback for me would be the remote control’s inability to control speed or feed rate.
I do miss the option of being unable to tweak the speed or frequency from the other side of the court. It’s not a deal breaker, though, just nice to have; if I hadn’t experienced that on my other ball machine, I’m not sure I’d have thought about it that much.
Is the fact you can only do topspin a gripe? Not so much for me. While you can’t get the Slinger to fire flat balls at you, that is easy enough to get from a hitting partner.
So while only topspin is a limitation, it is not something I have found myself missing when using the Slinger, as I enjoy the challenge of facing a ball that kicks up.
Slinger vs Other Ball Machines
The table below compares the Slinger Bag vs the Spinfire 2 Pro, the Lobster Elite Two and Tennis Tutor.
Slinger Bag Tips and Tricks
After using the bag a couple of times a week for several weeks, here are some tips and tricks I’ve thought of.
Carry a small Pozi screwdriver and some replacement CR2016 batteries in the bag. I have no idea how long the battery in the keyfob will last; I assume it is similar to a car key. But getting to the courts then having no way to start the machine would be painful.
Charge the Slinger regularly. I’d recommend charging every time before play. On one of my sessions, the battery ran out after 30 minutes of using it because I hadn’t charged it. I get around 3-4 hours from the battery. So don’t get caught out otherwise; you’re practising serves for the remainder.
Clean the bag often; I recommend vacuuming off the fuzz from the control panel and inside the ball machine to prevent excessive buildup. I use a Xiaomi mini handheld vacuum that does a decent job. You can also use a soft bristle brush to get it out of the harder-to-reach places.
Use high-quality unpressurised balls. My favourite is the Wilson Triniti which play great with a ball machine. I also use the Babolat Gold Academy balls, which are decent, but I prefer the Triniti overall. Slinger now partners with Dunlop for balls, but I have not tried them.
Get a second ball tube or basket. The bag has a tube that holds 20 balls, but if you can get two, use one in each hand, and then you spend more time training and less time collecting.
How I Would Improve the Slinger
- Enable speed and feed settings to be controlled from the remote
- Small LCD screen for battery % rather than LED lights
- Fix issue with not all balls falling into the machine (has already been addressed in the latest version)
Any other improvement ideas? Let me know in the comments.
Who is the Slinger Bag For?
The Slinger is the ideal bag for the improving recreational player or an aspiring pro, and it’s the sort of thing I’d have been fruitlessly asking my parents for as a Christmas gift when I was a kid.
If you’re looking for a personal ball machine that is easy to lift into the car, easy to move around on the court and delivers a consistent ball to improve your strokes, this would be my pick as you won’t find better for the price.
While there are more sophisticated machines out there, not everyone has $3k / £2k to spend on what is essentially a luxury toy that fires a tennis ball at you, so I like where this bag sits in terms of price: performance.
Yes, the Slinger Bag is still quite expensive at $800 / £800, but when you consider that many people spend $1000+ on an iPhone every year, this is cheaper and gets you moving around.
While it is more suited for personal use, I also think it’s a valuable string to the tennis coach’s bow.
Some coaches will likely be better off investing in a pricier machine, but for those one-on-one lessons where you want to watch a player’s strokes from behind or the side while they hit from the machine, it’s a helpful tool.
Likewise, it will be a good investment for coaches who travel around and run group training camps for juniors.
They can use the Slinger on the court with a group of kids and martial them from closeup without having to handle the feeds.
It’s also easier to carry around than the heavier machines, so if you do a morning session at one club and then drive to another part of town for an afternoon session, the Slinger lends itself well to that use case. They also sell a spare battery, so you can swap them out if you can’t charge it up between sessions.
- Very slick design
- All in one package
- Easy to transport
- Huge topspin
- Good price
- Balls do get stuck in the hopper
- The remote control can be flaky at a distance
- The oscillator is a bit cumbersome to carry additionally