HIGH QUALITY BATTERY MAIN SWITCH REPLACEMENT KEY: The key is made of ABS plastic and solid brass nut, the bolt is tightly connected with the brass part, the two will not easily loosen, rust and corrode, and have a long service life. MAIN SWITCH NATO BONE KEY SIZE: The Spigot for the key is 14mm long and fits most standard sized battery disconnect switches. EASE OF USE: The universal key disconnect switch is so neatly finished that it is easy to insert the key into the switch and turn it to select the Disconnect and connect battery. SCOPE OF APPLICATION: battery switch boot switch key is used to control the battery switch to prevent power loss and prevent car theft. Ideal for protecting cars, caravans and boats. NATO BONE KEY SET: This set contains spare keys for 4 battery master switches.