Milwaukee 1/2in Drive 3in Extension features the largest knurling surface, providing superior control during use. The knurling on the female drive end is designed to assist with hand-tightening and to maintain grip even when working with oily materials. Some extensions also include knurling on the shaft for enhanced handling. The chrome plating ensures excellent corrosion and rust protection, making this extension durable and reliable. All Milwaukee Mechanics Hand Tools come with a lifetime , underscoring their quality and longevity. Model Number: 43-24-9115