Slime Balls Screw Balls 99a 54mm Wheels Slimeballs Screw Balls Speed Balls wheels feature graphic art by Falu @falucarolei based on the original art by Jim Phillips on a hard, conical edge shape for firm coping lock, wide riding surface and high performance 99a urethane. All Slime Balls skateboard wheels are sold as sets of 4. Road Surface (Millimeters) 20 Wheel Width (Millimeters) 33