uxcell 2-Piece Plastic Air Pump Co-2 Diffuser One Way Check Valves Set, Red 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*Mad) Material : Plastic; Color : Clear, Red Weight : 8g 2 Pcs x Aquarium Check Valve