The Milwaukee Locking Bit Holders are engineered to be the most durable, strongest locking bit holders on the market. The intuitive auto-locking design fits all inserts and 1/4" hex bits and the small-profile quick release collar allows for easy one-handed bit tip changes. The MILWAUKEE? SHOCKWAVE? Impact Duty? locking bit holders feature two magnets to maximize magnetic transfer and holding power to the fastener and prevents drops. Each Milwaukee bit holder features an optimized Shockzone? geometry to provide up to 30x longer life and absorb 3x more torque to prevent breakage.