Feature: 1. Safety valve will open automatically when the pressure over the safe pressure. 2. Professional CO2 generator system with stainless steel bottle, better than simple plastic bottle generators. It is more reliable, steady, durable and efficient. 3. Bubble counter with check valve: Flow-rate of CO2 gas indication device and prevent water flow back into the regulator. 4. Solenoid valve: To control the on and off of CO2 generator system using with a timer(not included). 5. Come with a bubble diffuser, refine the bubbles and make it easy to dissolve in water and be absorbed by plants. Inject to your aquarium with CO2 quickly and easily. Specification: Main material: Stainless steel Main color: Silver 3 size optional: 1L: Height: 22.5cm; diameter: 10cm; thickness: 0.12cm; 2L: Height: 47cm; diameter: 10cm; thickness: 0.12cm; 5L: Height: 47cm; diameter: 13cm; thickness: 0.15cm; . Package List: 1* Stainless steel bottle 1* Solenoid Valve (1L Not included) 1* Bubble diffuser 1* Pressure reducing valve 1* Bubble counter with check valve 1* Filter 1* 1.5m tube 2* Suction cup 1* Manual Note: Excessive or double addition of raw materials and water is prohibited. Invert the bottle and disassembly are prohibited.