Brief Explanation on Modern Chinese Industrial Coffee Can Style Gas Mask Filters 

Thank you very much for the info, I'll update about this in the wiki

While most industrial Chinese filters use GOST, some are STANAG threaded. For masks catered for or was originally designed for use within the Chinese armed forces on the other hand mostly uses STANAG instead nowadays. The reason why some STANAG filters "fit" into some Chinese GOST filters are due to them having large tolerance and/or having plastic threads that bend to confirm to the thread of the filter. This is like smoking cigarettes; you can't see the bad effects in the short term, but you'll see them in the long term. Edit: I almost forgot to note that "normalised" or "standardised" threads don't exist. I once knew a Slovak that would go mad whenever someone mentions that STANAG filters fo GOST masks and vice versa. Funny stuff there.

The manufacturing tolerance must be large since DIN40 threads (4mm pitch compared to NATO 4.7mm pitch) also fits in perfectly. Edit: I also researched that parallel thread (ones used in gas mask) does not make a seal, so they use accurate threading or o-ring to make the seal. With a large manufacturing tolerance, I think its the o-ring and rubber gaskets in Chinese mask that makes a seal, so my DIN40 filter fits in because of its same height and diameter works just fine along with other NATO filters that have the same characteristics as such.

@@Isolierter_Hazim I'll measure the Chinese mask threads with a pitch thread gauge then get back to you. I really do not understand why people guess threads instead of actually measuring it.

Aye, they're safe to use as long as they're in date and not damaged

@@Isolierter_Hazim Thanks

@@Isolierter_Hazim Do they contain any asbestos at all though? :) Recently bought one, but I want to know if I can use the filter safely or if I have to use a polish fp-5 filter with it :)

Modern ones are asbestos free, no matter what brand they are. Just make sure that when you get it in good condition and you're good to go

@@Isolierter_Hazim Awesome! Thanks for the confirmation! With filters I don't know much about I like to be absolutely sure before I start using them, lol! Better safe than with lung cancer! Thank you! :D