uxcell Aquarium Fish Tank Air Pump Plastic One Way Non-return Check Valves 7 PCS Place in airline tubing between air pump and aquarium water to prevent water returning the air line. Protect you air pump by preventing aquarium water from back siphoning during a power outage. Product Name : Aquarium Check Valve;Use for : Fish Tank, Aquarium;Weight : 26g;Fit Tube Inner Dia : 0.6cm/0.24" Material : Plastic;Color : Clear, Red;Package Content : 7 Pcs x Aquarium Check Valve Hole Diameter : 2mm/ 0.08";Total Size : 5.3 x 1.5cm/2.1" x 0.6"(L*Max.D)