The US DIVERS Royal Master was only made for 2 years and was the predecessor of the Royal Aquamaster.  They are great breathers and much more rare than Royal Aquamasters.  This one is barn fresh.  Buy this one cheap and rebuild it yourself and save.  If you mention this at the time of purchase I will include a free silicone duckbill and a set of new mouthpiece valves at the time of shipment. 

Price $350.00 plus 17.00 shipping.