Respirator canister strap- original ?

[cvrwdvr]

I recently purchased this respirator canister with contents, and complete with carrying straps, but am unsure whether the shoulder strap would be an original issue to the canister, although it certainly appears to be period.
Anyway, I'll let the pics do most of the talking, but whereas the belt support strap is of webbing, the shoulder strap is of a heavy duty herringbone weave with a thin black line running along one side.
Any opinions as to whether this strap is an original respirator canister strap or improvised ?