This is a Replacement Ozone Soleniod Valve for Hess Ozone Systems. This valve is used to control ozone gas flow to the ozone contact tank. These valves are available in 120 VAC and 220 VAC versions. Check your valve's current voltage before ordering the replacement valve.
There is also a solenoid valve rebuild kit available that includes new seals, springs, and the plunger. This can be purchased as the valve rebuild kit.