MettleAir CVU-4-KV Viton/Kynar Universal Barbed Check Valve, Non-Return, Aquarium, 1/4" NPT (Pack of 10) Part #: CVU-4-KV Model: CVFF-N02 Tubing ID 2: 1/4" Type: Hose x Hose Barb Check Valve Please measure prior to ordering, photo enlarged for easy viewing, scale may be distorted