Rink Rat Crossbar Lite Goalie Hockey Wheels utilize Rink Rat's Interlock hub technology in conjunction with single-pour urethane for unmatched durability and performance. Interlock Hub Technology means that the urethane is poured through the hub for a stronger bond between the hub and the urethane. The Rink Rat Crossbar Lite Goalie Wheels are best used on a sport court, wood, or smooth concrete surface. Wheels are designed to fit any inline skate equipped with the 608 bearing size.