With this device, you can connect 1L, 2L cylinders such as CO2, , Mix cylinders to your existing aquarium fish CO2 tank regulator. Made of high quality aluminium material, sturdy, and long service life. Small and , easy to carry and store, convenient to use. Purpose: Connect 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. When placing an order, please be neutral and do not label. Material: aluminum colour: silver 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 a little different from the real thing. The measurement allowed error is +/- 1-3cm.