1/2" Drive Or 21MM : Our wrench extender is suitable for 1/2 inch drive or 21mm . This wrench extender adapter is great for . Both Tighten & Loosen Ways: Designed to extend wrenches with another wrench to more leverage. Used on different wrenches to loosen or tighten stubborn rusty and bolts, which can be removed more easily and save effort. Change to tighten or loosen, you just need to put it on the other side of the wrench. Steel Construction: Heavy duty construction of this wrench extender adapter prevents drive from slipping or rounding out. The heat-treated steel structure makes the wrench extension strong and . body wrench adapter. Heat treated steel, the protective coating prevents rust. This wrench extender can work great on rusty and bolts. Resists daily and tarnishing. for years of usage. Great Wrench Extender Tool: The wrench extender adapter can save your effort. Great for addings more leverage on stubborn and bolts and for getting into hard to reach areas.