【Compatibility】 The Yosoo CO2 bottle tank W21.8 CGA320 adapter converter is designed specifically for aquariums. It features a W21.8-14 female thread on one end and a CGA320 male thread on the other, allowing for seamless connection between CO2 bottle tanks and aquarium systems. 【Ease of Use】This adapter converter is extremely easy to install and use. Simply screw it onto the CO2 bottle tank with a W21.8-14 female thread, and then connect the CGA320 male end to the aquarium system. 【Variety of Types】 The CO2 tank adapter comes in two types or series. The first is the W21.8 converted to CGA320, and the second one is the CGA320 converted to W21.8. This offers the buyer with flexibility, catering to different requirements and making the adapter more universally usable. 【Superior Material】The CO2 tank adapter is made from brass, a material known for its strength, durability and corrosion resistance. Brass ensures a long lifespan for the product and significantly reduces the likelihood of leaks or malfunctions. 【Compact Size】The tank adapter has a diameter of 2.8cm/1.1in, which makes it compact and easy to handle. Its small size doesn't compromise its functionality but makes for easy storage and portability.