Thank you for viewing. Jaeger Sports J-BANDS (AGES 13 AND OLDER) J-Band Baseball Regular (for ages 13 and older) Color: Royal Blue J-Bands are inner muscle strengthening bands widely used in America by everyone from Little Leaguers to Major Leaguers. They can be used before pitching or during training, regardless of whether you're a pitcher or a fielder. Used by Kenta Maeda and Clayton Kershaw. A training menu document is also included, but please also refer to the Jaeger Sports website and YouTube for instructional videos. We would appreciate it if you could purchase this item understanding that it has been stored at home. Thank you.