TrainerOne™ Solo Tennis Trainer

The cord is tied to an anti-tangle swivel hook clipped to the ring on the base, and the hook turns as the ball spins to keep twists and tangles down.

Like any elastic trainer, the balls and cords wear out with use. When one gives out, swap in the spare and keep hitting.

To make them last, keep the cord off sharp edges and rough ground, store it out of the sun and wind it into the groove around the base when you're done.

Yes. The cord pulls the ball back toward the base, so line up with it and swing through firmly, a little low to high. A late or sideways hit comes back sideways, and on a soft hit the cord won't stretch enough to bring the ball back. Give yourself a few sessions to find your rhythm.

No. It's a reps machine for groundstrokes: contact point, footwork, a firm swing and a warm-up before you play. It won't train your serve or high volleys, it can't copy match timing and it won't replace your coach. What it gives you is volume. One rule keeps those reps honest: if a shot goes wrong, stop, reset and go again.

Two things help it hold its ground: the anti-slip pad underneath and the weight inside. Fill it all the way to the top, with sand if you hit hard, since it's heavier than water, or water for younger players and softer swings. Set it on hard, flat ground like a driveway, patio or garage floor. A half-empty base can slide, so top it up before you play.

Yes. Start a few steps from the base with short, firm swings and let the ball come to you, then step back as you start to connect. Your first sessions will have misses. Everybody's do.

You need a clear, hard, flat area long enough for the cord to stretch all the way out, plus room to swing: a driveway, patio, garage floor or court. Grass kills the bounce. Keep the cord's path clear of cars and windows.

It's simple to use safely: keep people and pets out of the cord's path, never stand on the cord, check it before each session (replace it if it looks nicked or worn) and have an adult around when younger players hit.