These modern classics make a great light, i wear my one as a prop....... or simply add it to your collection of STUFF
Historically, deep sea diving helmets ranged from the no bolt to two bolt to four bolt helmets; helmets with six, eight, or 12 bolts; and Two-Three, Twelve-Four, and Twelve-Six bolt helmets. Bolts being the method of securing the helmet to the diving suit. The helmet could also be secured to the breastplate (corselet) by bolts as in the case of US twelve-four helmets (12 bolts to the suit, four bolts seal helmet to corselet). The no-bolt helmet used a spring-loaded clamp to secure the helmet to corselet over the suit. Swedish helmets were distinctive for using a neck ring instead of a corselet, a pioneer of modern diving equipment but hugely cumbersome and uncomfortable for the diver. This equipment is commonly referred to as Standard diving dress and "heavy gear."[citation needed]
The US Navy Mk V helmet is still in production to order. In 2016 DESCO Corporation purchased the assets of Morse Diving International and began producing Morse helmets under the A. J. Morse and Son brand. The US Navy Mark V Helmet is available in either make with the minor manufacturing differences intact. While the Mark V is a US Navy design and all helmets should have been identical, models from Morse, Schrader, DESCO, and Miller Dunn all had differences. Brails from a Miller Dunn are difficult to fit on another maker's helmet. Early Miller Dunn Mark V helmets had gussets on the interior radius of the air and communication elbows. Schrader Mark V helmets used yellow brass castings instead of red brass like other makers. Schrader also canted their spitcock body. The standard Mk V weighs approximately 55 lb (25 kg) complete.[6]
A small number of copper Heliox helmets were made for the US Navy by the Second World War. These helmets were Mk Vs modified by the addition of a bulky brass carbon dioxide scrubber chamber at the rear, and are easily distinguished from the standard model. The Mk V Helium weighs about 93 lb (42 kg) complete (bonnet, scrubber canister and corselet)[7] These helmets and similar models manufactured by Kirby Morgan, Yokohama Diving Apparatus Company and DESCO used the scrubber as a gas extender, a form of semi-closed rebreather system, where helmet gas was circulated through the scrubber by entraining the helmet gas in the flow from an injector supplying fresh gas, a system pioneered by Dräger in 1912.[8]
Four companies produced Mark V diving helmets for the US Navy: Morse Diving Equipment Company of Boston, Massachusetts, A Schrader's Son of Brooklyn, New York, Miller-Dunn Diving Co. of Miami, Florida and Diving Equipment and Salvage Co. (later Diving Equipment Supply Co.)