Update: I posted a new video at the end of this report.
I feel like I'm starting to become an expert on tenugui, i.e., Japanese hand towels. These things are generally in the range of 33cm by 90cm (or thereabouts) and are made of thin cotton and dyed to exhibit various patterns and designs.
I'm not going to go into the history of tenugui or the multitude of uses to which they may be put. Info is readily available online if you're so inclined. They seem to be quite popular with kendo players, though. For folks into SM and Japanese style rope bondage, you can't get more traditional than a tenugui with blue polka dots used as a gag.
These just happen to be my favorite, followed by the ones with red polka dots.