Jardin Air Pump Plastic Non Return 4-Piece Check Valves for Aquarium, Red/Clear Product Name : Air Check Valve; Use for : Aquarium, Fish Tank Color : Red, Clear; Material : Plastic Hole Outer Diameter : 4.5mm/0.177"; Overall Size : 53 x 14.5mm/2.1" x 0.57" (L x D) Weight : 15g Package Contents : 4 &times; Air Check Valve