TEKTON SIB92103 1/2 in. Drive Triple Square Impact Bit Socket Set with Rail, 9-Piece (M6-M12, MT14-MT18)TEKTON impact bit sockets have both a high-visibility laser size marking and a permanent stamped marking that wont wear off. Theyre designed for use with both friction ring anvils and detent pin anvils. Our 2-piece bit socket design allows us to optimize the steel alloys, heat treatments and forming processes for the bit and socket separately. This results in a tool thats higher performing and more durable than traditional 1-piece impact bit sockets.Sizes are marked both with a high-visibility laser marking and a permanent stamped marking that wont wear offTriple square (XZN) S2 steel bit tips are machined to precise tolerances for strong engagement with fastener heads2-piece design allows bit and socket to be optimized separately, for a more durable tool than traditional 1-piece designsDrive end is made of 4140 chromium-molybdenum (Cr-Mo) steel and properly heat-treated for use on impact wrenchesTwist-to-lock socket rail organizes and securely holds sockets in place, both for in your toolbox and on the go6-piece, 1/2 in. drive triple square impact bit sockets: M6, M7, M8, M9, M10, M123-piece. 1/2 in. drive tamper-resistant triple square bit sockets: MT14, MT16, MT18Socket railDimensionsDrive Size1/2 in