PA VNR-I Series Check Valves. Flow regulating valve. Allows a one-way flow, preventing the back flow. Sturdy construction in stainless steel. O ring Viton. Return action of piston carried out by a spring. Minimum pressure loss. Rapid intervention at minimum flow variation. 150 Bar max pressure. 1/4" to 3/4" female threads. AISI 303 stainless steel body. Viton seals.