Andibro 10 Pcs Aquarium Check Valve, Aquarium Air Pump Accessories Non-Return One Way Fish Tank Line Check for 3/16 Inch Airline Tubing Fitting Clear

Very useful for co2 thank you.

You can't have too many reverse flow valvesThey're put together reasonably well and work as you would expect albeit cheaply madeThe price is reasonable and they're worth a try

Great value , good quantity. I have put these safety valves on all my air pumps for safety I am sure they will all work in a power cut ....I am hoping to never find out

Biggest load of rubbish, don't waste your money on these, barely let any air through at all, eventually took valve of another pipe on main tank, to find that one worked fine, AVOID AT ALL COSTS, THEY DONT WORK