Awesome ultra thin socks which I use primarily for climbing.  Most people go barefoot in climbing shoes, but within a few months, the shoes stink so badly, you have to buy new ones.  So I decided to try these to see if they were thin enough to mimic going barefoot, but preserve the life of my shoes.  They seem great so far.  They are super thin and comfortable, with no "helpful" padding.  Basically they are like a second skin so they create a thin, but effective barrier between your feet and your shoe.

I have also used them for hiking.  I have zero-drop trail shoes and really don't want extra padding to "help" me.  I want to feel the ground.  These work great for that as well.