Abstract: A training device for use by baseball players to help correct certain undesirable arm motion technique which might lead to catastrophic injury. The device utilizes one or more gravity-activated switches connected in a circuit within a case of a strap-on assembly. The gravity activated switches are oriented a specific way within the case, and the case strapped to a specific location of the arm so that certain undesirable arm motion will cause the gravity actuated switch to close and an alarm buzzer to sound. Conversely, the switch may be oriented so that the buzzer only sounds if the correct technique is practiced. The device is particularly useful in a preferred training method for baseball pitchers.