DOUBLE SEGMENTS - sintered diamond bar segments SOFT BOND - suitable for grinding hard concrete GRIT SIZE & SET - #18/20 grit includes 4 grinding discs GRINDING METHOD - use wet or dry COMPATIBLE - fits onto National Flooring Equipment floor grinders (Helix Grinder, 8274-4 Grinder, GP500, GP700, GP3000 Grinder) Diamond grinding tooling designed for National Flooring Equipment floor grinding machine, comes in a set of 4 pieces. #18/20 grit with soft bond ideal for hard concrete. Compatible with Helix grinders, 8274-4 grinders, GP500, GP700 and GP3000 grinders.