ISTA Intense Flow CO2 Bubble Counter suction cup hanging - aquarium Solenoid diffuser 1. Compact in size, and crystal clear acrylic makes it unnoticeable. 2. Elegant design adds grace touch to your CO2 supply system. 3. Strict quality control assures no leakage. For 4/6mm tube (Does not contain) For 4/6mm co2 tube (Does not contain)