The J&M magnetic hydrant wrench is custom-made to fit hydrants with a magnetically protected security nut. The wrench engages the free-spinning security nut (the type found on most NYC and surrounding area hydrants) allowing you to open and close the hydrant's valve stem. Caution: use the wrench only on hydrants for which you have all appropriate permits. Unauthorized use of hydrants may subject you to fines and your equipment to confiscation by the local Authority Having Jurisdiction.