The price includes a 4% credit card fee. If you pay by check, money order, or bank wire, the discounted price is $399 delivered within the contiguous United States.  
 
If you have an early World War 2 dated Mark V or even older, then this style of air control valve would be correct to display with your helmet. The “Y” style air control valve with dual female fittings is featured in the 1916 US Navy diving manual.
 
This valve is in very nice visual condition, with a consistent patina to the brass. There are no manufacturer's names or stamps on it. The valve is complete with the eyelet to bolt it to the bastard stud of your Mark V.
 
The price includes a 4% credit card fee. If you pay by check, money order, or bank wire, the discounted price is $399 delivered within the contiguous United States.