Here's a group of tougher-to-find rubber/plastic styles. From left to right:

Continental Rubber Works RC-1 - a tougher to find transposition bracket replacement spool to begin with, BUT this one is unmarked completely making it that much more unusual.

Small slot top cable. Completely unmarked, but difficult to find.

Continental Rubber Works R-5 (transposition steel carrier bracket replacement style). I don't see these turn up often, especially in excellent condition like this one.

Canadian Pacific Railway telegraph style. Double petticoat with conical skirt and spherical dome. Hard, PVC plastic-like material. These seem to be unique to the Canadian Pacific Railway.

All four are in good shape apart from typical wire wear. The spool has some surface staining and a few rubs around the top of the pin opening.

$30 USD plus shipping for the group of four. I'm always happy to trade for early Canadian glass or Canadian-made porcelain insulators. I accept PayPal, or personal cheque from any member of ICON or any collector with whom I have dealt before. Please feel free to contact me with any questions or for more photos, and look through my other items or unsold sales stock to combine shipping on items.