Essential power tool accessory for hand-held power and cordless drills and drill presses. One tool with 4 key sizes for tightening and loosening chuck. Fits all major brands. Steel with baked enamel finish. Sizes: #1, #2, #3, #4. Pilots: 3/8-15/64 In., 3/8-1/4 In., 1/2-7/32 In., 1/2-1/4 In.