The Jaw Dropper’s adjustable jaws allow users to work on both the pipe union nut and the tap back nut with the same wrench.In the closed position the bottom half of the jaw acts as a stop when tightening / removing the union nut.When the sliding jaw is dropped, the tap back nut can be tightened without having to turn off the water supply or drain the system. The Jaw Dropper’s slim design ensures maximum accessibility