Train Spin That Plays. The MOI-75 is a spin-development training baseball built for pitchers who want to improve carry, spin efficiency, and feel at release. Designed with approximately 75% of the moment of inertia (MOI) of a regulation baseball, the MOI-75 is engineered to rotate easier during throwing drills, helping athletes train cleaner finger pressure and more efficient spin through release. If a pitcher gets around the baseball or loses direction through release, the ball tends to sail high — providing immediate feedback during catch play, flat grounds, and bullpen work. The result is a training tool that helps reinforce staying through the baseball and creating cleaner rotation out front. Built with a premium leather cover and specialized weighted core, the MOI-75 delivers authentic baseball feel while creating a unique training stimulus for modern pitching development. Ideal for pitchers focused on spin quality, carry, command, and overall throwing efficiency.