Features: Adopt carbon steel, wear resistant and has a long service life. The handle is nonslip and comfortable to hold. Use to tighten or loosen the chuck. Perfect for most electric drills and power tools. The ratchet function makes changing the drill bit more efficient. Two sizes help you work perfectly. Small head diameter: 12.7mm, big head diameter: 17.5mm. With a positive and negative ratchet switches, it can rotate forward and reverse, and quickly loosen and tighten the drill chuck, which is simple and convenient. Used to adjust how tight or loose the chuck is, and the drill bit may be changed more quickly thanks to the ratchet function Specifications: Material:Carbon Steel Diameter Of The Two Ends: small end 12.7mm, large end 17.5mm Package Includes: 1Piece Chuck Drill Key Wrench note: Please allow 1mm errors due to manual measurement. Due to the differences between different monitors, the picture may not reflect the actual color of the item.