Vintage Army WWII Era US Military Metal Film and similar items

Looks rustiy but actually there is very little, it is a stainless steel painted over with brown, there is more rust although only light on the few buckles than the rest of the area put together. Most likely used to transport and store trainging films as the feature fillms were on larger reels. Inside width is 4" so holds however many reels you can fit in that measure. Not the most common item and as you might see loose film reals it could also be very functional. Apparently had a carry strap on top but it is gone.