Features This is a one-way check valve, which can prevent air backflow and ensures excellent air tightness. Made of high quality copper, high strength, high temperature resistance, very durable. Only suitable for air, not applicable to water or oil. Useful accessory for your machine, 5 pieces per pack, enough for long time use. 1/4 inch internal thread, suitable for many machines. Specification: Material: Copper Colour: as shown in the picture. Quantity: 5 pieces Fluid: Air Port Size: 1/4" Size: Approx. 4 x 1.5 cm/1.57 x 0.6 inches. Weight: approx. 163g Features: 1/4 inch internal thread, suitable for many machines. Made of high quality copper, high strength, high temperature resistant, very durable. Only suitable for air, not applicable to water or oil. This is a one-way check valve, which can prevent air backflow and ensure excellent air tightness.Useful accessory for your machine, 5 pieces per pack, enough for long time use. Package includes: 5 x Air Check Valves Package List