I've seen some that are X-shaped when installed. The center of the X sits between pins, the "legs" of the X are under tension and squeeze the pin. No plastic, just a thin metal. The legs are not perfectly straight, like in the letter X, but are slightly curved toward each other. When not in place on pins, it looks like a very skinny "8".
Ive seen these on equipment, but I've never stumbled upon them from a manufacturer. I just tried looking for you, but came up empty.
That doesn't help you directly, but at least it is another style to look for.