Powell Peralta Bowl Rider Skateboard Wheels Width: 37mm, Hardness: 95A Formula: Powell-Peralta Original we have been able to keep the Powell-Peralta Original Formula continuously ahead of all other MDI based wheels in rebound and abrasion. This provides skaters with the very highest in performance at a price point that makes them a real value. Powell-Peralta Original Formula is an evolution of the white, MDI urethane we pioneered in 1977. This family of urethanes has grown to become an industry standard, and because we develop our own formulas in-house, All Powell-Peralta products come with a warranty