Yes, I agree with Jay. In fact Burt, I bet this is a topic a lot of folks have spent some time thinking about. I agree with Jan as well, by the time the cloth jackets came about, I think the pulls were standard. In fact I have a mint B-15A missing one, and would bet it might have one time had one that fell off, was removed, etc. I had done a search myself when I obtained it to see if they were on others, and the super majority of B-15 and B-15A originals I looked at at that time had them. I bought a repro Buzz Rickson blue N-1 Navy jacket a couple years ago, and had a very lengthy discussion with Charles at HPA about the pull. The ad’s all showed the pull as the same cord material as the jacket, but when my jacket arrived, it had a black leather pull. Lo and behold Charles provided me with extensive research revealing the original N-1’s had both and BR decided to revert to the leather ones because they were a bit earlier in the production runs. By the time the OD N-1’s arrived, they were all made of the cotton material.
But back to A2’s, my bet is they were added by the pilots or wearers themselves.
it is the little things in life.