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Programmable robots allow you to create a sequence of different balls. So the robot may feed you a ball to your forehand, then 4 balls to your backhand, etc. It is customizeable so you can make any sequence you want.

Adjustable Height refers to the feature where the robot lets you adjust the head height, so you can shoot balls from different heights. It would require a long neck, or a platform with an adjustable height. If your robot doesn't have this feature, you can use stools of different heights (for small robots that sit on the table).

NOTE: This is not the same as adjusting the angle of the head. Some robots can adjust the angle to shoot higher or lower, but still don't have an adjustable head height.

Continuous Feeding is a feature where the robot has a net attached which will catch the balls that you hit, and feed it back into the robot automatically. This is much better than having to turn off the robot and collect the balls and put it back in the robot. In theory, the robot can then keep feeding you balls forever without stopping. This feature must come with the robot out-of-the-box, without having to make your own custom net system.

Oscillating is the feature where the robot's head can move and aim balls in different locations without having to stop the robot and set it manually. This is a crucial feature for footwork drills that make you move to different locations.

Mount refers to the mounting style of the robot. Does it mount onto the table, or is it movable onto other platforms, or is it free standing?

Ball Wheels refers to the number of wheels that shoot the ball out. Better robots will have 3 wheels to make bottomspin, topspin, sidespin and combinations of these spins. With one wheel you cannot make a no-spin ball.