I wore this for the first time yesterday under a cotton skirt from the Gap and over bare legs, and it slid up the entire day.  I kept having to re-adjust it, which was very frustrating since I was out shopping with a friend.

The length on this is also 16" (it's not clearly marked on the description) if you order the standard one.

I know that I purchased the right size since any smaller or bigger wouldn't fit, but this one just didn't work for me, and I'm frustrated that I spent money on it.  I'm going back to Farr West slips, which, while more expensive, always seem to work great.