The 1950s US Divers Over Pressure originally came with a small tube going down the supply side hose to the metal mouthpiece.  It is very rare to see one complete today.  The little hose became more brittle more quickly than did the original corrugated hoses.  Most models were retrofitted with a three piece hose assembly like what you see on mine.  This regulator does not seem to be as collectible as many other USD models but I find it very aesthetically pleasing with the shiny chrome front can and satin rear can.  It is also interesting to note that this was probably the last USD model made that used the separate screwed on exhaust housing for the duckbill like the Broxton.  Later models made by USD like the Stream Air did away with this trait probably for ease of manufacture.

Click here for the action pictures of the Over Pressure.