Uxcell 8-Piece Plastic Aquarium Check 1-Way Valve Air Pump Co2 Diffuser Set, Red/Clear Aquarium Check Valve; Use for : Fish Tank, Aquarium Hole Diameter : 2mm/0.08"; Total Size : 5.3 x 1.5cm/2.1" x 0.6"(L) Material : Plastic; Color : Clear, Red Weight : 30g 12 Pcs x Aquarium Check Valve