I've got three of them. The only qualm I have is consistency of sizing. I've got a larger head than most (that's how come I be so smrt), so finding a good cap is difficult. The first Walz I bought fit perfectly. The second one was simply too small. The elastic was completely stretched and it would always ride up to the top of my scalp and eventually fall off. The third fit somewhere between the two. It was still too small, but doesn't fall off.

Just something to consider for the braniacs.