I can't identify a source or name for these brass contact sleeves (I guess
that's what they are).
They are 1 3/8" long and hold a male size 8 coax contact () in the center.
It kinda turns the coax connector into a triax connector by adding another
contact surface around it.
They come from some medical equipment I am trying to fix (physical repairs).
I have linked to a couple pics I took.