Necklace Tubes and Tube Bails are the most popular bails for rattail.
Rattail cord is excellent for Kumihimo. The smooth, shiny texture braids well and looks great. Just try to avoid soaking it, because the color may run when wet.
More Changes for Rattail Satin-Like Cord from Rings & Things:
The manufacturer of rattail closed a while ago, so it was unavailable for most of 2016 and 2017. We nixed some possible replacements that were rough or wimpy. We found a temporary new source for the GOOD quality smooth, shiny, rattail satiny cord ... and (spring/summer 2019) we'll be replacing this soon with an even better source!