“THE ULTIMATE PLYOMETRIC TRAINING TOOL ATI Training Shoes are designed to utilize plyometric disciplines to target calf muscle training, subsequently building mass and definition, as well as increasing the quantity of fast twitch muscle fibers. Results include an overall increase in vertical jump, reactive leg strength, jumping skill, body coordination, and range of motion. Shoes come with an HD-DVD training video, a laminated training card to bring to your workouts, and a stretch stap for pre/post stretching. ATI SHOE FEATURES - Increase vertical jump 5-10 inches - Lower 40 yd. dash time by 2/10ths of a second - Increase reactive strength, jumping skill and coordination - Create maximal power output - Increase fast twitch muscle fibers - Increase calf mass and definition - Increase range of motion” Only worn a few times inside. Mens size US 12 As seen on Seinfeld, lol.