As above, I can confirm the adaptors fit straight on once you remove the extinguisher trumpet, The advantages of using an extinguisher is that they syphon from the bottom of the cylinder rather than the top so you will get liquid CO2 into the pistol cylinders, I used these on all my Walthers (my CP2 cylinders used to take approx 10 - 15 sec to get up to fill weight, once you've weighed one it becomes easy as will take the same amount of time on each fill, I used to leave some in the pistol cylinders and just before filling release the remaining CO2 to quickly chill them, Saved putting them in the freezer and ensured a full fill. Have fun with it they really are great pistols.

Nige