All coal miners lamps in the UK were required to have magnetic locks so they could not be opened underground. Theseare parts for miners lamp locks.
The lock is in a brass casting on the side of the fuel vessel. The bung fits into a threaded hole at the base of the lock body and it retins the spring and the locking pin. When fitted by us to a lamp the slot on the head is removed so it cannot be unscrewed. These are often drilled out to remove the locking pin. The magnets we sell are placed on the base of the lock body and pull down the spring and pin allowing the fuel filler flap/locking plate to be opened.