RockCandy Core….. The Ultra hard outer riding surface is the Ultimate formula for speed. It slides great and loud and fast. The 70D RockCandy core spins fast and precise like no poured bearing seat wheel can, and the 84B surface takes it up a notch on speed as well. These wheels are fast as hell and like no other wheel because it’s the only one on earth made with this incredible combination. Recommended for smoother surfaces.