The bag is clear on one side so you can use your GPS or whatever thru the bag, the plastic is thick and tough, but remains flexible. The design is mechanically elegant in that it is extremely simple, yet foolproof.
The manufacturer has mostly been supplying these bags to the military, but is ready to start selling to the sports crowd. They claim waterproof to 140'.
Far superior to the established dry-bags I have seen thru the usual suppliers, but limited in sizes and usually only available through the manufacturer.