The SDBA's a type of frogman's rebreather breathing set. Many of the world's navies and army marine corps have used it since 1971. It's made by Mercury Products (contact information) in Billingshurst in England. The SDBA's described on this page. The breathing bag's square with rounded corners, on his chest, exposed. Its absorbent canister's cylindrical with flat ends, crosswise on his belly, in a rubber sheath. It's a loop of wide corrugated breathing tubes; one of them originates at each end… (More on Sdba)