The Flex Edge discs attach to the Flex Edge Holder in the same manner as the regular Power Lock discs, but are designed so the sanding disc overhangs the holder. The holder has a 1/4" diameter shank. By having approx. 1/4" overhang around the holder, the Flex Edge disc is not as aggressive as the regular Power Lock discs and is less likely to "dig" into the work piece. The Flex Edge discs come in 2" and 3" sizes and have a padded reinforced area around their edges to provide support for the overhang of the disc. The Flex Edge Discs come in 60, 80, 120, 180 grits only.