All legend firs stages are sealed.I believe that on the first stage, if you can see the hexagon adjustment screw, it is not a cold water version. If the adjustment screw is covered by a silicone diaphragm than it is a cold water version(supreme) This seems to be how aqualung and, even before, Us Divers handled the sealing of the main diaphragm and spring to make the first stage cold tolerant.