Lee’s 2-Way Plastic Airline Valves (12 pack) – A pack of twelve small adjustable valves for standard aquarium air tubing. Each valve has two barbed ports and an adjustable knob, letting you fine-tune or completely shut off the airflow to air stones, bubble walls, or sponge filters. They’re made of non-corrosive plastic and are essential for controlling aeration and reducing noise or turbulence in your aquarium.