The design of the lightweight respirator introduced in 1943 underwent modification towards the end of the Second World War, these changes combined with further upgrades in the immediate post war period meant that the respirator used by the British Army in the 1950s was subtly different to that first issued in World War Two. We have covered the wartime lightweight respirator here so rather than repeat myself, I am going to focus on the changes that make up the post war Mk III lightweight respirator:
The most obvious difference is the change to the muzzle of the respirator, where a screw thread has been added:This was to enable a Mk 7 screw microphone to be added to the mask. In reality this seems to have not been used, instead earlier Mk IV T-Mic masks continued to be issued.
Other changes to the mask included a new rubber composition that was less irritating to those with dermatitis and an increase in the number of outlet holes in the rear of the speech diaphragm which reduced exhalation resistance and improved the clarity of the wearers voice; however the most obvious change in the post-war period was the adoption of a new filter canister, painted in a dark sea-grey colour:These canisters were distinctly smaller than the wartime examples:Whilst Danish Civil Defence canisters can also be found for these masks, this is definitely a British example of the canister as it has the /|\ mark and came from an unissued respirator, still in its original stores box! Altogether there are at least seven subtly different variations of the lightweight respirator, with masks undergoing refurbishment to differnt components; therefore many masks are found exhibiting elements of various different marks.