IVY Classic 44850 3/8" Square to 1/4" Hex Mega-Magnetic Impact Driver Adapter, 1/Card 40X THE PULLING POWER: Mega-Magnetic Bit Holder features 2 powerful magnets which create 40x the pulling power of an ordinary magnetic bit holder (Mega-Magneticis a Registered Trademark) TWO POWERFUL MAGNETS: The internal magnet (#1) holds and magnetizes the bit while the outer circular ring magnet (#2) powerfully holds your fastener in place - see photo IMPACT PLUS: One piece stainless steel construction with aluminum slide is designed to withstand the high torque of drills and impact drivers(Impact Plus is a Registered Trademark) VERSATILE: Allows a 3/8" square impact driver to function as a 1/4" hex Mega-Magnetic bit holder, works with all 1" hex insert bits PATENTED IN USA: Size: 3/8" square to 1/4" hex, Length: 2-1/2", Shank: 3/8" female square