The bosch 9 piece s extra hard screwdriver bit set is a phillips head bit set designed for universal screw-driving with screwdrivers and drill drivers across a wide range of everyday fastening tasks. Each bit is manufactured from s2 modified steel and undergoes an optimised heat treatment process to achieve extra-hard quality. This makes the set a reliable choice for tradespeople and contractors who need consistent performance across varied materials and fixings. The tapered torsion zone is a key design feature, absorbing force and vibrations during screw-driving to cope with torque peaks without compromising the bit. The -inch external hex shank ensures a secure connection with strong torque transmission in both three-jaw chucks and internal hex tool holders. Features and benefits: s2 modified steel with optimised heat treatment for extra-hard durability tapered torsion zone absorbs force and vibrations to handle torque peaks external hex shank for maximum torque transmission in chucks and hex tool holders suitable for use with screwdrivers and drill drivers nine-piece set with multiple ph1, ph2, and ph3 bits for versatile coverage specifications: bit length: 25mm net weight: 0.137Kg contents: ph1 x2 , ph2 x4 , ph3 x2 , quick change universal holder x1