I have these spectra socks in the crew version, which I wore on a four day backpacking trip...they were a fail. Under the ball of the foot, instead of a patch of cushioning, there are three lines of looped (spectra?) fabric. These lines gave me terrible blisters! Luckily, I had a pair of standard, regulation merino sleep socks which I limped around in for the rest of the trip. So that's the con; the pro is that, as advertised, they didn't wear out.