FPPI TrimFit^® OS&Y valves feature a bronze body, cast iron hand wheel, and steel, stainless steel, and brass components for extended service life. OS&Y valves (outside stem and yoke) are perfect for fire sprinkler system monitoring, as they allow for immediate identification if the valve is "OPEN" or "CLOSED". When the valve is open, the stem is visible above the hand wheel. In the closed position, the stem is concealed inside the valve body. Can be fitted with external tamper switches for central station or panel monitoring. UL Listed, FM Approved.