Tri-Wing Bit Set Tri-Wing: 0, 1, 2, 3, 4, 5, 6, 7 and 8. All 1/4” hex. x 25mm. overall length, complete with quick release 1/4” hexagon bit adaptor. All Kennedy screwdriver bits have a hardness of 58 - 62HRC. High alloy chrome molybdenum steel for use on hand and power tools.