Package includes: 15 pieces air pump check valves, necessary parts for your air pump aquarium O2 system.Please DO NOT use them with CO2 system. Function: Airtight, a one-way non-return safety valve, greatly protects the air pump by preventing backflow of aquarium water during a power failure. Application: Compatible with Air Hose from 4mm inner diameter standard aquarium, perfect for fish tank, fish tank, fishing tackle store, etc. Made of high quality plastic material, anti-aging, not easy to break, sturdy and durable. durable in use.Please use a paperclip to push it from the inlet side to the outlet side when the outlet inside is blocked. Air hole diameter: 4mm; Overall Size: 5.4x1.4cm(L*Max.D), Color: Red.
