3/8" thickness urethane, medium density, 5/16"-24 male thread. Sanding pads are perfectly weight-mated to Dynabrade tools, for achieving consistent swirl free finishes. High quality backup pad; weight mated for smooth running and minimal tool vibration. Ideal for PSA-type disc adhesion; remove abrasive adhesive paper liner and press abrasive to vinyl-face sanding pad. Quick disc removal.