Two sizes help you work perfectly. Small head diameter: 12.7mm, big head diameter: 17.5mm. The double-head design is suitable for most chuck, and the ratchet function allows you to work faster. With a positive and negative ratchet switch, it can rotate forward and reverse, and quickly loosen and tighten the drill chuck, which is simple and convenient. Made of high quality Metal, wear and has a long service life. The handle is non-slip 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, Weight: 0.48060773116 pounds, Manufacturer: Ynusgeyx