The 4 Pound Stinger 1 Medicine Ball is popular among golfers and tennis players. Use on the court or field for high volume endurance sets and locomotion drills.All balls are 14″ in diameter impact absorbing and moisture resistant. The casing is sewn from 18 oz. flexible vinyl coated polyester. The standard colors are black and gray but many custom color designs are available. The casing design and construction insures that the implement remains dimensionally stable and balanced. The Dynamax trade secret and craftsmanship utilize the casing to retain the various fibrous cores under tension so that each ball regardless of weight has the friendly feel and will absorb high velocity impact. Each ball carries a warranty against stitch and lacing failure.