MILWAUKEE SHOCKWAVE Impact Duty Locking Bit Chucks are designed to be the most durable and strongest on the market. The intuitive self-locking design fits all 1/4 in. hex drive inserts and bits, and the low-profile quick-disconnect collar allows for one-handed bit changing. The new locking bit chucks contain two magnets to maximize magnetic transfer and retaining force of the fastener to prevent it from falling out. Like all SHOCKWAVE Impact Duty accessories, each chuck features SHOCKZone geometry optimized to achieve 30X longer life and absorb 3X more torque to prevent breakage.