The No 200 contains a silicone treated Buna-S rubber poppet, designed to open easily and be more durable than O-rings. Being flexible, they cannot leak. They are manufactured from a one piece cast brass body. The unique strainer consists of a helically wound stainless steel spring wire which is durable and cannot corrode. Each valve is tested twice for casting integrity and backflow prevention. All valves are 100% American-Made and built to last.