The Playmate GENIE Upright Ball Machine is a powerful tool for teaching tennis. Realistic game situations with up to 7 shots can be practiced. Groups of students can practice drills such as ground-stroke, approach, lob to 2 lines feeding the balls every 1 and 1/2 seconds. Or if you are practicing at home, you can throw 2 ground strokes followed by an approach shot followed by a volley followed by a lob. Don't forget, this ball machine is perfect for teaching doubles teams too! You can purchase this machine now and buy an upgrade later that will let you use it with your iPhone or iPad. Key features of the Playmate GENIE include 7 Distinct Programmable Shots, 7 Shot Delays, Programmable Random Shot Sequence (Great For Enhancing Ball Recognition Skills), Upgradeable and Interchangeable (works with ALL controllers), Holds 300 balls, Variable Topspin and Backspin, 7 Position Programmable Electronic Direction with Programmable Random, Variable Electronic Height, User-Friendly Controller, SERVE LIFT friendly, 2-Function Remote Control (On/Off with drill reset), 3-year Limited Parts Warranty.