Air injection check valves on 126?

[Rainman]

Almost there! I have in front of me two multi-colored check valves which were removed from the vacuum lines on my 380 se. One is black and blue with a thin white spacer between the two halves, part #001 140 1760, also marked on same piece is KYS 4.0003. The second is green and white with a red spacer between the colored halves, part #001 140 3860, this is also marked KYS4.0008 Both are double ended with nipples on each end for insertion into vacuum line. Please tell me 1) what function they perform, 2) their properly installed direction/position for proper functionality,3) a new part number for replacing them. (Do they go bad?) . I recently presented them to a MB dealer for replacement and he referred to them as "strainers". His initial replacement for one was incorrect (he called me back the next day). On returning he sold me two much, much smaller parts with nipple sizes that did not seem appropriate for this application. He guaranteed he had the right ones this time. I am very near to having my vehicle running just fine however I do not feel well about the parts he provided me for replacement. There are still minor problems with the idle and performance in my vehicle and I just wish to be certain these components are not a contributing factor. I have located the replacement part for one of them in fastlane, however no picture is provided so I cannot compare for clarification. If someone out there could please provide some insight into my problem it would be very much appreciated.

Thanks again, Rainman