Varco Supply carries two brands of brass piston air valves: Rubinetterie Italiane Velatta (RIV) and Metaltecnica (MZ). RIV and MZ are two industrial Italian manufacturers with over 130 years of experience in the wastewater industry combined! RIV air piston valves feature a round and brass pneumatic cylinder while MZ valves feature a rectangular and aluminum pneumatic cylinder. Though these valves are otherwise nearly identical, it should be noted that spare parts for rebuilding these valves are name brand specific and NOT interchangeable.