Customized variable inertia speed training - the most efficient way to increase your bat speed. The algorithms that power the dynamic programming come from years of research by leading sports scientist, Dr. Sasho MacKenzie.

Be guided you through scheduled workouts while tracking Stack weight, rest, recovery, and performance gains. This information allows future workouts to be adjusted behind the scenes, so your training is optimized to maximize bat speed gains.

Track key performance metrics such as Stack Speed, Distance Potential, Bat Speed and Grit Score. Easily share your progress and gains.

Dr. Sasho MacKenzie has worked with multiple MLB teams as a biomechanics/bat fitting consultant – including the L.A. Dodgers.

Dr. Sasho MacKenzie is the research practitioner behind the world’s top golf coaches - his work and theories have driven a scientific, evidence-based revolution in golf instruction and movement training.