Review on 🐟 Pawfly Aquarium Check Valves: Non-Return Air Pump Accessories for Fish Tank - Black | Enhance Your Aquarium's Efficiency! by Florencia Fernandez

I use them to aerate water bottles that I drink through a hose (like the CamelBak system but from a bottle instead of a bladder). I drill a hole in the cap for the hose and another for one of those check valves. This prevents the bottle from spilling but allows air to pass through so the bottle doesn't collapse when I drink. These valves are very simple and easy to clean. The two-piece body is threaded and the valve itself is held between the halves. I use a short length of plastic tubing on the valve nipple to fit snugly in the hole I drilled in the bottle cap.