The badge is attached to the red flash only on my cap. When the flash is tucked inside it will only go down as far as the bottom lug. It would seem that if the badge had a slider it would be able to go through the flash and into that loop of thread, thus holding the flash and badge in place. If you look at all the old photos the badge sits so that the badge is half one side of the red piping and half the other. This can't be done with a lugged badge.
Surely this forum must be the best place to find a member who had a RMA cap badge with a slider
