One Way Air Pump Check Valves for Bioflock Specification: Price for Per Pcs Color : Yellow, Red, Clear Material : PlasticHole Outer Diameter : 4mm / 0.2″, Overall Size : 53 x 14mm / 2.1″ x 0.6″ (L*Max. D) For more information Call Us : 01674368628 OR message Us: https://www.facebook.com/TechnoPowerB