The bosch 8 piece sx extra hard screwdriver bit set is a versatile phillips bit set designed for everyday screw-driving tasks with both screwdrivers and drill drivers. Manufactured from s2 modified steel with an optimised heat treatment process, each bit delivers extra-hard performance suited to a wide range of applications. The 1 4-inch external hex shank ensures a strong, secure connection with maximum torque transmission in three-jaw chucks and 1 4 internal hex tool holders. The tapered torsion zone is a key design feature, absorbing torque peaks, force, and vibration during screw-driving to protect both the bit and the fastener. At 49mm in length, the bits are well suited to general construction, joinery, and first-fix or second-fix work. Features and benefits: s2 modified steel construction with optimised heat treatment for extra-hard durability tapered torsion zone absorbs torque peaks, force, and vibration during use 1 4 external hex shank for maximum torque transmission in three-jaw chucks and hex tool holders suitable for use with screwdrivers and drill drivers set of 8 bits covering ph1, ph2, and ph3 sizes for versatile everyday use specifications: length: 49mm net weight: 0.150Kg contents: ph1 2x , ph2 4x , ph3 2x