Bones 100’s 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 Bones develops their own formulas in-house, they have been able to keep the Bones 100 formula continuously ahead of all other MDI based wheels in rebound and abrasion. 100’s formula is a Bones exclusive. Also Includes a set of Independent Abec 7 Bearings. Featuring removable non-contact labyrinthe shields, grit blocking cage, stainless steel races and balls. Set of 8 bearings with spacers and SpeedRings.