serious point
Alexis, If you were issued such kit to use why do you feel the need to take it to bits to see how it works? this really is kit your life depends upon. take it to your squipper to service/repair.
At least read the AP.
I don't belive there was ever such a thing as a Type P mask. P and Q were sizes. How terms have become corrupted. a bit like Hoover is a vacuum cleaner.Or should we call them Dysons today!
£150 is probably a bargain. we may have paid that just for the string. particularly if it was supplied cut to length with a knot on the end!!!