For use in either pressurized or canister systems, Whitecap EPA Compliant Deck Fills use elastomeric valves and for over a decade have proven to be more reliable than traditional ball and spring type valve systems. When used with canister systems, the valves inside the deck fill merely act as a secondary pressure relief backup. Designed to fit in all existing deck fill locations on OEM boats, Whitecap deck fills are proven to be reliable in a full range of temperatures and weather conditions.