Testing FP-5 Filters With Other GOST Gas Masks

As requested by a viewer, I am testing Polish FP-5 filters on several more GOST masks to prove that they work across all GOST threads. I have now tested the FP-5 filter on a GP-5, PMG, PMK, and CM-3, and it has worked on all of them. Therefore, we can conclude that the FP-5 filter is a great universal filter for almost any 40mm mask.