Aquarium CO2 Regulator Waterproof Carbon Dioxide Regulator with Big Gauges Bubble Counter Solenoid for W21.8 Interface Cylinder Multicolor EU Plug W21.8 Interface Features Compatible with CO2 cylinders with W21.8 interface, can effectively reduce gas output in the cylinder, a nice accessory for planted tanks and aquarium fish tanks. With a bubble counter for displaying real-time air output, backflow-proof design, preventing water from flowing back to the bottle. Big dual gauges design, clearly display the cylinder pressure and outlet pressure; and the volume of air output or close can be controlled by the fine-tuning valve. Premium aluminum alloy construction, durable for use; equipped with a power adapter, has stable working performance, low power consumption and low noise. 12V DC solenoid with non-leaking function, ensuring secure use; normally closed, can deliver gas when connected with a power source. Specifications Color: Multicolor Material: Aluminum alloy Working Pressure: 15mPa Output Pressure: 0-0.3mPa Input Voltage: AC 100-240V Output Voltage: DC 12V Product Size: 10.7 * 8 * 4cm/ 4.2 * 3.1 * 1.5inch Product Weight: 348g/ 12.2oz Note The tank and CO2 cylinder showed in the pictures are not included. Package List 1 * Regulator 1 * Wrench 3 * Rings 1 * Adapter