Different fisheries had different requirements so various models of helmets developed.DESCO makes the Abalone, Agar, Fisheries, and Browne Commercial helmets on the Sponge breastplate and shell.The helmet came stock minus communications and with a simple head butt exhaust valve.Variants As stated above "Sponge" also referred to a class of helmets.
The top and breastplate are one unit permanently joined.
Still a buyer must be wary when bidding or purchasing online.
In some cases the seller is not knowledgeable in the item they are trying to sell.
The Lightweight Fisheries has the Mark V exhaust valve.
The Browne Commercial helmet has large screw in Acrylic windows, an integrated air control valve, and a low profile air inlet/communications block.