So I accidentally set off my PFD today and bought a new CO2 canister to re-arm it.
In the picture below of the actuation mechanism in my life jacket I'm confused about the function of the black rotatable switch. It can be rotated about 270. Can anybody enlighten me as to the function of this black rotating dial or lock or whatever it is? I have looked online under the name of my life jacket which is a Marlin Explorer 150 and also under the name on the valve being UML micro but can find nothing. Any help would be greatly appreciated.

If I understand it properly - don't do anything with it. It simply holds the value unit to the vest itself through the manifold. Or something.

Sounds good guys thanks for that :-)