This Seahorse regulator and tank combo dates from the 50s.  It is very similar to some of the homemade rigs made by early divers using Oxygen diluter regulators from WWII aircraft.  This diving setup was sold out of Pittsburgh Pa. in the 1950s and was not very elegant.  The tanks on this specimen were last hydroed in 1967.  The company apparently took the surplus oxygen regulator and waterproofed the diaphragm, added a Seahorse logo and mounted it to a solid manifold and sold it as a diving rig.  I do not know anyone personally that has dived one of these, but perhaps with the aid of some friends and a new harness from the Allan custom harness works I will some day.