3 Pc. Power Extension Socket Bits for Drills (CHROME, 2) Power extension bar sizes (inch): 1/4 Hex by 1/4; 1/4 Hex by 3/8; 1/4 Hex by 1/2 Driver width: 1/4-inch Chrome vanadium heat-treated steel Ball-bearing lock Turns any power drill into a power nut driver