My 3,5 years old loves this cap, as well as I do - no hair pulling, easy to put on and take off, stays in place on my son's head during swimming class. It is lycra, so it is no waterproof - but also no crying because it does not catch child's hair.
Also, I love the customer service - I've contacted the owner to check when can I expect the package, and she made sure to ship it ASAP for me to have it delivered before our swimming classes started, even since she was leaving for her vacation at the time. Thank you!