Baden Ballistic Leather Pitching Machine Baseballs, (One Dozen) GENUINE - Leather cover for a true authentic look and feel SEAMS - Flat Kevlar seams add durability for long-lasting use in pitching machines and hitting drills SIZE - Official size (9") and weight (5 oz.) CORE - Duralock and rubber core which helps with shape retention and strength SHIPS - by the dozen (12 baseballs)