I bought this cap because my other (ClubSwim) silicone cap kept sliding up and feeling like it was going to fall off, and my hair would hang out the back, even if tied up.  I've had no problems with this one so far...it seems to be the same cut/style but for some reason it stays on better.  The white is kind of pearly which is cool!

I've taught swimming for 35 years and this is the best cap I've found.  Very stretchy so will fit most heads & people with long hair... from 1st graders to adults.