Won't Slip
I bought this when it was $7.79 just to try it out.  It's adjustable which is great because I have a small head.  The first time I wore this overnight, it did not slip off.  It's a good value for the money.  The price has increased since my purchase in November.  I plan to get another one when/if the price goes back down because it is definitely not work $13.99.
Rating: 5 stars