Hello, newb on board. I recently got ahold of some Bauer 059183A filters. In doing some searching I found they were for use with the P21 filter system. Is this a system that is still in use? I ask because I know nothing about compressed breathing air and didn't want to throw these away if someone could use them. If you think they could be put to use, I will open a classified add. Thanks for any help or guidance. b