I think the straps were part of the Army field kit or a stock item and not part of the splint itself. Splint was wrapped in paper and then in boxes. Funny thing is actually that those that are wrapped and sealed cost more, but you ruin the value if you open it, so all you can see is a bulky thing wrapped in paper.
I actually had the opportunity to buy one still wrapped as well, but seemed like overkill to have 2.
I’ve got it hanging on the wall as a sculptural piece.
R