TEMPERED TOOL STEEL STANDARD EXTENSIONS: Designed for professional use FULLY HARDENED EXTENSION PRODUCTION: Engineered for long life under constant demanding use PROVEN TEMPERING PROCESS: Developed to provide increased durability PRECISION EXTENSION HEAD: Designed and machined for an integrated fit HIGH-QUALITY TOOL STEEL: Helps to ensure consistent top quality performance JOBSITE-TESTED BOSCH ACCESSORIES: Proven engineering, best materials and innovation