Product Description Pack of 10 red one-way valves air are manufactured in made from durable plastic materials and designed to fit any environment. most gas pumps; common aquarium air without making noise. Prevent your pump from air to run water through your pump during water changes or when the power is interrupted. Note: Please do not place the air valves in the CO2 system as the high pressure will cause them to crack and leak. Fit standard 4mm hoses Good airflow and no restrictions Plastic hard rigid Durable and aging-resistant Long working time without noise How to install 1. Before use, clean and dry both sides of the tube to hang the valve well. 2. Check the flow direction of the valve to make sure it is placed on the correct side. 3. Carefully attach the pump check valve to the pump. air to the tube and connect it completely. Tips: If the valve restricts the airflow in both directions, please insert something into the hole on the side. input to push the valve. After that, the valve would allow the air to flow in the right direction. Read more Good in prevention The air check valve protects the pump at low pressure. air by preventing aquarium water from siphoning off during a power outage. Convenient application Fits standard 4mm hoses. Can be used for aquariums, fish tanks and hydroponic gardening etc. But DO NOT place them in a CO2 system. Safe and durable Clear rigid plastic materials allow you to get rid of inlet breakage easily or leaks. air. Work for a long time without making noise. Type Check valve Air valve connector Quantity 10 pieces Color Red Connector diameter 4mm