The Bathtub key is fully waterproof (ideal for use when Scuba Diving) The case is moulded bakelite, plated brass mechanism sealed with rubber gaskets. A British key presumed to be Model 10. as parts are marked 10F/ 7741, 10A/ 7790,10A/ 7789 and 10F/ 606. An interesting key with slow action and boxy low frequency click. The key has at least one keen collector with several examples in his possession. Mine cost me Half a Crown (12.5p) in1962 brand new in waxed paper packaging which had a wonderful smell.