A super rare helmet, thought to be less than 20 ever made

This being the only one with a peppermill modification, and aid to help divers ascend and descend quicker. The Heinke MRO was developed for recovery of mines (especially magnetic mines) to a depth of 55m (180ft). The outfit is a self-contained, semi-closed system that uses a mixed gas supply of nitrox. The system was successfully trialled for the Royal Navy and was to replace the older Siebe Gorman MRS diving apparatus

In 1961, C.E. Heinke merged with Siebe Gorman, but the MRO’s were never produced in commercial numbers, as new technologies and diving equipment soon superseded it. Originally, it was thought that about 18 MRO sets were produced in 1958, and then put into storage. However, one or two additional MRO helmets have been discovered with exhaust and communication modifications.