Made from rugged S2M tool Steel. 100% made in the U.S.A. Custom heat treated for strength and durability. Manufactured to tight tolerances to ensure accurate fit and full fastener engagement. Insert bits have a retaining ring notch. 1/4" hex body. Fits all standard multi-bit screwdrivers and power drills. Torx® is a registered trademark of Acument Intellectual Properties, LLC.