Earthwing 65mm Slide A Superballs The “Slide-A” urethane compound is custom to Earthwing Superballs designed for technical downhill sliding. All other slide wheels are compared to these, but are not even close. These have years of proven reliability, and industry praise. Initiating slides, and hooking up in the transition between the slide, and roll is predictable. The wear is consistent, without pitting, or excessive chunking, quiet, confident, and behaved. Specifications: 62mm height, 42mm width, 25mm contact patch, 100 durometer, centerset hub, with rounded edges. Set of 4 wheels.