BONES WHEELS 100's Original Formula is the great grandson 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, we have been able to keep the BONES 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. Our Original Formula is another BONES exclusive.