3 Ways Metal Co2 Flow Controller - Tri Regulator Brass splitter Solenoid aquatic for 4/6mm air line.  Provides the convenience in distributing air flow up to 3 different tanks.  you can supply Co2 to 3 aquariums, without having to purchase additional Co2 tank!  only for electronic regulators. Precisely adjust the rate of air flow. No air flow leakage.