The carbon dioxide bubble diffuser is made of zinc alloy, and it is safe and non-toxic. It can produce the bubbles in the fish tank and not occupy much space in your fish tank because of the small size. It is sturdy and durable for long time use. Features: Save your space: the diffuser is small, and it will not occupy much space in your fish tank. Increase bubbles: the diffuser can be used to increase carbon dioxide bubbles in fish tank. Easy installation: the carbon dioxide bubble diffuser is easy to install, convenient to use. High quality: made of the zinc alloy, safe, non-toxic. Study and durable: the diffuser is sturdy and durable for long time use. Specifications: Condition: 100% Brand New Material: Zinc Alloy Color: White+ Silver Style: 1#, 2#, 3#, 4#(Optional) 1#: Diameter 12mm, Bulbs 2#: Diameter 16mm, Bulbs 3#: Diameter 12mm, Without Bulbs 4#: Diameter 16mm, Without Bulbs Size: approx. 122*62mm/ 4.80* 2.44in(for 1#, 2# style) approx. 50*62mm/ 1.96* 2.44in(for 3#, 4# style) Weight: approx. 79~104g/ 2.78~ 3.66oz Package List: 1* Carbon Dioxide Diffuser 1* Screw 1* Fixed Mount Note: 1. Please allow 0-2cm error due to the manual measurement. Thanks for your understanding. 2. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object. Please take the real one as standard.