M9A1 Respirator VS M9 Clones

Comparing the US M9/M9A1 respirator to it's various clones and copies.
The M9 was a very advanced gas mask for when it went into American service in the late 1940s, a comfortable face-piece, balanced weight, tissot tubes and an oral-nasal cup and a quick to change 60mm filter.
M9 style masks were used by South Korea, Japan, Sweden, Finland, Yugoslavia/Serbia, Iraq and Egypt, there may be other users as well.
Finland and Yugoslavia made their own improved versions as well, so in this video we compare the M9 to the M9 clones.