Easy-Aqua 2 liter Co2 cylinder with solenoid regulator. Only used once. It has been recharged with full CO2 again. It comes with insta regulator. It is good for 20 to 50 gallons planted aquarium. Material: Usually constructed from high-strength aluminium alloy to be lightweight, non-magnetic, and corrosion-resistant. Usage: Suitable for providing a steady and reliable CO2 supply for planted tanks to encourage lush growth.