The Markwort Speed Sensor MPH Baseball measures your pitching and throwing speeds. Now you can see how you measure up to the major baseball players and practice your way to the big leagues. Official size and weight of a regulation baseball, but used as a training aid for any age or skill level. Measure distance between pitcher and catcher with included measuring string and choose one of 8 predetermined distances (20', 30', 40', 46', 50', 60.5', 70' and 80'). GripSense technology begins to record the speed automatically the moment the ball is released. For pitching throwing training only, not to be hit with a bat or on hard surfaces. Measures speeds up to 120 MPH.