Brief overview[]
During the 1980s, Czechoslovakia found a new use for its old respirators that had been stored in various bunkers over a few decades. The CO-1 was a 1950s issue respirator that had, by the 1980s, been replaced by more advanced masks. Instead of manufacturing more masks, the Czechoslovak authorities decided to take the CO-1 out of storage and modify it to accept MOF filters, thus increasing the longevity of old mask stocks.
Mask[]
CO-1 on left, CO-1/R on right
The CO-1/R is essentially a CO-1 with modernized intake and outtake valves. There is otherwise no discernible difference between them.
Stamp showing its a modified version, although hard to make out, the stamp says '1987'
CO-1/R masks have a small pink ink stamp on the side of the facepiece to denote their modifications.
Comparison. CO-1 (top) CO-1/R (bottom)
It would appear that during the mid-life update, most of the valve assembly was removed and replaced. The aging exhale valves were removed and replaced with newer ones and the mask received a new intake valve assembly, this one done to ensure compatibility with newer models of filter, chiefly the MOF series. When comparing the CO-1 and CO-1/R valve assembly side by side, it would appear the CO-1s intake threading is longer (see comparison photo).
Other Kit[]
Identical to a CO-1 kit (Shiny metal tin, green cardboard tin, cotton haversack)
Filter[]
The filter for all CO-1/R kits was the MOF series. If one considers the above CO-1/R was modified in 1987 and one assumes all others were done during a similar timeframe, the specific MOF model would likely be MOF-4.
Other details[]
Although unconfirmed, the '/R' is often speculated to mean rezervní (Czech for 'reserve'), this is because the CO-1/R was most likely never issued; only to be used in dire situations, such as a nuclear attack or when one's original mask was broken.