The AJ FHL1 is a simple design hydrant lock to deter unauthorized individuals from tampering with the operating nut on a fire hydrant. The locking device is constructed to accommodate either a conventional or barrel lock, which will allow a system to remain uniform. The FHL1 works simply by securing the cover to the operating nut device with a pin. This will allow the cover to rotate freely around the operating nut device so that the operating nut can’t be engaged. American made product.