This fish tank CO2 atomizer has excellent performance on fish photosynthesis. Vey easy to install and use. It has benefit to fishes. Creates very fine Co2 bubbles for diffusion into water. Features: 1. Made of high quality material, which is non-toxic, safe, energy-saving and eco-friendly. 2. Safe lock system design can effectively lock the CO2 tube and water tube to prevent loosening. 3. The design is simple but effective. Two colors are availble to choose. 4. Adopt reserve osmosis technology to diffuse CO2, which can increase the dissolved rate and save the usage of CO2. 5. Sugested to be installed under fish tank bottom. Specification: Condition:100% Brand New Material: ABS Type: Green S, Green L, Brown S, Brown L(optional) Small Size: approx.4.3 x 3 x 1.3cm/1.7 x 1.2 x 0.5in(L x H x Dia) Large Size: approx.4.5 x 4 x 1.8cm/1.8 x 1.6 x 0.7in(L x H x Dia) Weight: Approx.19g~24g/0.7oz~0.8oz Package list: 1 x Carbon Dioxide Diffuser Note: 1. Please allow 0~1 inch error due to 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. .