Fits standard 1/4 to 3/4 inch and metric 7-19mm nuts and bolt heads.Turns any drill or power screwdriver into a power socket driver. Auniversal socket can be adjusted immediately to grasp various shapes nuts,screws,hooks,lag screws and bolt heads etc. Made with chrome-molybdenum steel spring pins that retract to the shape of most objects. This practial and convenient tool will replace your entire socket set making your daily life easier and happier. We promise 1-year free duty replacement or refund if any quality problem arises.