NorKut Grinding Discs, 3", Grit 36, Package of 20 NorKut grinding discs are made with rugged NorZon grain so it cuts fast and lasts long. Resin bonded to a unique backing which resists cracking and breaking, these discs can be down to any size up to the 1 core. Use the cores to grind “pinch” welds and other hard to reach areas. Two quick change mandrels allow NorKut to be used on most popular tools. 7/16-20 thread is for use with hand held pneumatic grinders while the 1/4 mandrel is for use on automotive drills. 3657 No -