Lexair KEYSTONE® ALUMINUM VENT VALVES are manufactured to the NAVSEA standard 803-1749102/1749103 Rev B. They are offered in both round and oval style bodies and feature a working pressure of 15 PSI (tested to 30 PSI). These “MADE IN THE USA” products were designed to be used as an airtight or watertight closure. They are compliant with several MIL Specs and are used on all NAVY ship classes. They are available in 2-1/2” through 30” round or 7x3” through 30x20” oval sizes. They are typically used for HVAC controls plus intake and exhaust air applications.