Shop › CRB.XRx.RC31 Image 1 of 1 CRB.XRx.RC31 $345.00 Cobalt RC31 pad shape for Vintage Corvette Single Pin and Twin Pin Calipers and various GM. Compound: Select Compound XR1 XR2 XR3 XR4 XR5 Thickness: Select Thickness 13.0mm 20.0mm Quantity: Add To Cart Added! Cobalt RC31 pad shape for Vintage Corvette Single Pin and Twin Pin Calipers and various GM.