• Air check valve;use for :aquarium, fish tank
• Color : black, clear;material : plastic
• Hole outer diameter : 4.5mm/ 0.177″;overall size : 42 x 10mm/ 1.65″ x 0.39″ (l*max. d)
• Weight : 4g
• Package contents : 1 × air check valve

Protect you air pump by preventing aquarium water from back siphoning during a power outage.Place in your airline tubing between your air pump and aquarium water to prevent water returning down the air line.