This Super Multi-Clamp is a larger multi-clamping section with more gripping surface than the SC-GRSMC. For mounting heavy items. The SC-GRSSMC Road Series Multi-clamp is perfect for Gibraltar Road Series (1 1/2") tubular racks. Made from Super-hard steel. Perfect For mounting toms, accessory arms (5/8" to 1-1/4"-diameter) to standard 1-1/2"-diameter rack tube.