Universal 7/8 Hex Drive 21 mm Oxygen Sensor and Vacuum Switch Socket by Lang Tools®. Make servicing your vehicle’s exhaust system fast and easy with this handy tool. It will help you keep your exhaust working as it should. Thanks to its thought-out design, this tool provides the ultimate blend of convenience, functionality, and dependability. Made from top-grade materials for strength and durability, this quality exhaust system service tool is bound to provide you with many years of trouble-free operation.