With this device, you can connect 1L, 2L cylinders such as CO2, and mix cylinders to your existing aquarium fish CO2 tank regulator. Made of high-quality aluminum material, sturdy, durable, and long service life. Compact and lightweight, easy to carry and store, convenient to use. Connects to M10 gas cylinder to open and close the gas. Specification: Item type: CO2 cylinder adapter Model: M10X1 to W21.8-14 (DIN477) Note: W21.8-14 interface is only suitable for Europe, South Korea, Australia, and New Zealand Material: Aluminum Color: Black Package Contents: 1 x CO2 Cylinder Adapter Only the above package content, other products are not included Note: Light reflection and different displays may cause the color of the item in the picture to be slightly different from the real thing. The measurement allowed error is +/- 1-3 cm.