Ratio Free Diver Helium Safe Nylon Automatic Diver's 1066KE20-33VA-BLK-var-NATO1 1000M Men's WatchRatio Free Diver Helium Safe Nylon Automatic Diver's 1066KE20 33VA BLK var NATO1 1000M Men's Watch Does the helium valve excite you? Well, its useful for commercial divers only; that too, only them doing very deep saturation diving. You need to live underwater for that, in habitats filled with a mixture of breathing gases, one of which is helium. The helium molecules are small enough to pass through the water humidity protection of the watch and