Sodastream Filling Station Ball Valve Adapter For Tr21-4 Carbonator Thread Cylinder With Large Cylinder CO2 W21.8-14RH / DIN477 Clock sensor 250bar/3500psi. Aluminium adapter with Tr21-4 thread (pin knob). W21.8-14 threaded connector in gold colour Stainless steel braided hose with a length of 36 inches. How does it work? Follow these steps: If possible, put the soda spray bottle in the refrigerator so that it cools for 1 to 2 hours first. Make sure that the on/off valve (left) and the drain valve (right) are closed (90 degrees relative to the ball valve body) and turn the pin knob (black adapter) of the small cylinder adapter upwards (counterclockwise). (Insert gasket into connector) Connect gold connector to large CO2 tank. (Spin with a key. ) Connect the small cylinder to the black adapter. Turn the pin knob down to lightly touch the cylinder pin (clockwise) (pressing the pin too hard will stop the gas supply through the check valve when the filling cylinder is 6 mm wide) Open the large Co2 tank valve. Slowly open the on/off valve (left) (counterclockwise) and close it after 2-3 seconds, then open the drain valve (right) drain the remaining gas in the small cylinder, then remember to close the drain valve (right) after this step). Carefully open the on/off valve (20-30 degrees counterclockwise) to carry out the charging process for 30-60 seconds, then close the large carbon dioxide cylinder valve (make sure the on/off valve is open) After filling, set the release knob to the highest position and open the drain valve to release the remaining gas in the hose. After inflation, unscrew the small cylinder. Repeat the filling process for each cylinder.