Strengthen your throwing arm while using the same javelin you throw in competition! The Javelin Weight increases resistance through a specific range of motion. The weight simply slips over the tip of the javelin up to the balance point and tightens snugly for a sure fit. Does not affect thrower's grip. Please Note This item CANNOT ship to P.O. Boxes, APO, or FPO Addresses. It CAN ONLY ship to a Street Address.