A Siebe Gorman tin on brass Admiralty 6 bolt diving helmet with admiralty pattern number 7985 stamped above the face plate on the Helmet.
The helmet, corselet and brailles have matching numbers, there is no number on the face plate.
Complete with front and rear hanging posts, salvage lashing eyes, spitcock, inlet and outlet valve, telephone elbow and blank and internal comms. The internal comms have chin button and microphone speaker.
Weighs approx 27kg.
This helmet belonged to a Navy diver who qualified in Standard dress in 1939, before the term 'Clearance divers'.  He used this gear up until he was 80 with the Historical Diving Society.  He was involved in the diving on Tirpitz it would seem as there are a couple of items from her in with other bits of his.