The Ace deep socket is required for turning nuts onto bolts when the bolt extends upward into the socket. It gives you a little extra reach when tightening or loosening a stubborn nut or bolt. This deep socket is made with easy-to-read markings that increase visibility even in low light. Features: Made of alloy steel with a highly polished finish 6 Points of contact make it easy to grip hardware without stripping it Drive size: 9.5 mm drive Socket size: 17 mm Style: Deep