Interesting.
dandelang has his out so he can hopefully give you good measurements. Mine is on the wheel and it is a bit of a pain to get to .
I would estimate it to be about 40" long, maybe 3/4" to 1" wide and 1/2" high or so with a "groove" on the inside of the circle and small lip on one edge. It is item 2 in the drawing
dandelang included in the original post. I imagine it would be made in one strip from some appropriately flexible but durable material and and then bent around the inside of the ring while it was being glued in.