This kit contains all joiners you need to aerate an aquarium. Just add an Air pump, Air Stones and Silicone Tube and you will have bubbles galore.
Airline Check Valve
Airline T-Joint (black)
Airline Control Valve (black)
Airline T-Joint (clear)
Check Valve - This is a one-way valve to stop water from flowing back into your air pump. Take the valve and blow through it - if air can pass through the device then attach the tube on that side to the tube coming from your air source.
Airline Control Valve - Twist the tap until the desired amount of bubbles is achieved. It can also be used to balance airflow when multiple airstones are used from the one air pump.