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The Slinger Bag: New Tennis Tech

As life gets back to normal and courts open up, quarantine would have not been the same without my trusty Slinger Bag by my side. I was an original Kickstarter backer back in May of 2018. I was able to hang in with the creator Joe Kalfa, and the Slinger Bag team from May 2018 to March 2020 (when it was finally delivered to my doorstep). Every campaign has their ups and downs, their positive and hopeful backers and also their impatient backers - this ball machine was worth every minute of waiting. 


The Slinger T-One Launcher is an all in one remote-controlled portable tennis ball machine and equipment storage unit, and it is an absolute blast, literally and figuratively! Quarantine would not have been the same without it. I was able to work on my volleys, footwork and hand eye coordination during quarantine until my local courts in Los Angeles reopened. 

Slinger Bag Kickstarter 

The Bag

The bag is a one stop shop for everything you need for a practice or warm up session. I am able to put it in the trunk of my car, drive to the park, roll it to the court (waiting period permitting), place my bag, get my racquet out, turn on the bag, and practice my technique to my heart’s content. Setup literally takes two minutes and the wait time from pressing the “on” button to your remote hitting the first ball is 10-15 seconds. Charging takes 5-6 hours, and with the battery life that 4-6 hours depending on the speed and feed selection.  The ball capacity is 144 balls, and my package came with 72 Wilson Triniti/Slinger branded balls. The weight of the bag without the balls is 33lbs/15kgs, and with the 72 balls, it was about 45lbs/20.4kg. The size of the machine according to is, “Height: 33 in (83 cm) Length: 20 in (51 cm) Width: 18 in (45 cm).”

 Slinger Bag


The ball launcher caters to beginners to advanced players depending on placement, speed selection, feed speed, and launching angle. The remote control makes it easy for wireless starting and stopping for water breaks, speed/feed adjustment or angle modifications. Depending on placement on the court, you can work on your forehands, backhands, volleys, overhead smashes, serves and returns. When you add the oscillator unit you can also mix up both wings of the forehand and backhand. The Slinger community / social media also provides ideas on how to creatively use the machine and get the most out of it.


The Pros of the Slinger Bag

Sleek and thoughtful design:

the bag is well thought out to fit the needs of any tennis player. There are a total of four compartments for your keys and wallet, your racquet and equipment compartment, a side compartment with a built in USB charging outlet and another compartment to hold water bottles and towels. Each compartment has their own symbols, to keep everything organized. There is also a clip attachment to attach the telescopic ball tube that the Slinger team has designed. 

Slinger Bag

Ease of setup

The T-One Launcher is a no hassle set up process, and you are on the court warming up or in a practice session before you know it. I’ll keep this pro short, like how fast the setup is for the Slinger.  

Amazing value

Although I got the Slinger for the Kickstarter price of $239, I would pay for the current MSRP for $765 the Grand Slam Player package. The T-one Launcher and all the accessories that came with it bring 10x the value of the money you’re paying.

Heavy Topspin

If you ever wanted to know what playing Rafael Nadal is like, this machine gives you a small Costco sample of what it is like. The topspin is going above my shoulders and I’m 5’11. My arms definitely feel sore after torturing myself at this height, after increasing the angle and speed of this beast. This also helps me improve attacking a ball on the rise.

Slinger Bag

“Ball Boy” Mode

Instead of going to my ball hopper picking up two balls, putting one ball in my pocket, practicing my first serve, then my second serve, and then going back to the ball hopper to repeat the process over and over again. The Slinger bag has the “ball boy'' function, where it constantly feeds to you at the Deuce or Ad-side, and you can practice serving in record time. The launcher does penalize you though by feeding another ball to you if you go beyond its feeding “serve clock”. 

A Warm-up Partner

Due to the quarantine I have not competed in tournaments or USTA league matches as of yet, but when I do get back, I will have a good warm-up partner in this bag, especially in tournaments. When you arrive early to a tournament you can either hit with a pro (for a fee) or kindly ask one of your opponents if they are free (if you want to see their weakness or vice versa by all means go ahead). Sometimes that luxury isn’t available though and Slinger is the next best thing. Although the machine lacks variety in spin, it is still very helpful in warming up all of your shots.  

Slinger Camera Holder

This accessory is a hidden gem. Basically, it’s a holder for your phone, and it has a three pincer grasp with an adjustable latch. It can attach to the Slinger bag’s trolley handle, the tennis net or around the chain link fencing. Filming my practice sessions provides awesome feedback to myself, and my coach so I can improve at a faster rate. 



The Cons of the Slinger Bag

Entry and Exit of the Vehicle could be a challenge

An older gentleman asked me at the courts of how heavy the machine is, and at 45lbs/20.4kg with balls it may not seem all that heavy, but with the frame of the machine, it could cause some injury to players putting the Slinger Launcher in the car, and getting it out of the car. Maybe the Slinger team can show a video of proper ergonomics to handle the bag. 

Slinger Bag

Ball doesn't shoot when balls are still left

Sometimes the ball gets stuck or a ball isn't shot out when there are balls still in the Slinger. This is pretty rare, but when it happens I have to run over and shift the balls a bit.


Oscillator is a bit of a hassle

I love the Oscillator, but it can be a hassle to carry around, the bag acts like a backpack almost and when you put it around the Slinger bag it hits the floor when you are moving. There is no designated clip or latch on the bag like the ball tube. 


The Ball tube is a bit flimsy

I love how the ball tube has a telescoping feature, but the telescoping feature can be flimsy and when you apply force to pick up a ball, the ball tube folds in instead of picking up the ball. 


Possible Improvements

Add spin variety

Although the topspin is great, players have a lot of variety, I wish the machine could provide a flat ball and/or slice as you encounter these types of players frequently as you reach higher rankings.


Add Wilson Triniti balls separately

Adding Wilson / Slinger Triniti Balls as a separate order: As of now the Slinger branded Wilson Triniti balls can only be bought with a Slinger package. A Wilson Triniti case of 72 balls is at a MSRP of $139 on If Slinger can add an option to buy the balls alone for a reasonable price that would be helpful, or a subscription base model for ordering the tennis balls.


Bottom Line

If you're looking for a portable, functional and new age ball machine....look no further than the Slinger Bag


🎾 Written by Mike Malig, Gear Guru

[Editor's note: Our goal is to review gear that we think is worthwhile and qualify as either truly innovative, a great value or better yet, both. As we try to adhere to these standards for our own products, we know there are some great companies and products out there. We want to share our honest thoughts on them to help ADVance tennis forward!]




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