All Kennedy screwdriver bits have a hardness of 58 - 62HRC. High alloy chrome molybdenum steel for use on hand and power tools. Mechanics' Bit Set All?1/4" hex. x 25mm overall length, complete with magnetic spinner handle, 1/4" hexagon bit adaptor and 1/4" square socket adaptor. TX: T6, 7, 8, 9, 10, 15, 20, 25, 27, 30 and 40. Crosspoint: No.1, 2 and 3. Flat: 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5 & 8mm. PZ: No.1, 2 and 3.