The new Undercover Antirocker aggressive skate wheels are stylish and durable. They are 47mm big, 65D hard (rockhard) and have a flat profile. These wheels don't need a separate hub, as their overall hardness will always keep the bearings in place. Antirocker wheels are placed in the middle of the frames to prevent the risk of the wheels catching (wheelbite) when learning or doing slides. Unlike soft polyurethane wheels, these will slide on any surface - curbs, ledges, rails etc. Used with bearings which will allow these wheels to rotate and not wear flat spots when sliding on curbs. It also helps on the streets and in skateparks to better roll over transitions that would otherwise slow you down. Antirockers aka grindwheels makes sliding safer and way more fun!