Low-Profile Back-up Pads for Dual Action/ Random Orbital Sanders 
Soft density low-profile pads utilize 1/2" thick foam for fine finish sanding and offer moderate conformability.
Medium low-profile pads have 1/2" thick urethane foam for intermediate and finish sanding.
Firm density low-profile pads utilize 1/4" thick urethane foam for flash and seam removal.
Available with NorGrip / Velcro faces.
The designs are shock resistant and have a fiberglass backing plate with a riveted  5/16"-24 threaded shank for added strength and increased heat resistance. 
Available with a standard 15-hole pattern for vacuum-assist sanding.