To start off, I normally ski in a light cushion sock or even a medium cushion from Smartwool and Darn Tough. Merino wool is the only way to go with ski socks, and socks in general in my opinion.
The Le Sock is composed of 58% Bamboo Rayon, 24% Merino Wool, 15% Nylon, and 3% Lycra. I have a size 9.5 foot and I have these socks in a medium, which ranges from 6-8.5 US Men. I thought they were going to be too small, but they stretch quite a bit and the large may have been a bit baggy on my feet.
Merino wool is awesome for many reasons, including its warmth but especially its antimicrobial properties. These socks have been awesome. I have yet to pull a sweaty foot out of my ski boots after a day of wearing these, which is unheard of for me.
The Le Sock compares closely to an ultra light cushion from Smartwool. If your boots are a bit roomy / packed out, this may not be the right sock for you. I had to double up with my Le Sock and ultra light cushion Smartwools to get a comfortable fit. If you are trying on new boots, this would be an awesome sock to get fitted with.
The other awesome aspect of this sock is the lack of seams. I have not had any discomfort or bunching while wearing these. I hate when the seam rests oddly on my toes,and that problem will never occur with the Le Sock.
I highly recommend this sock if you are looking for the thinnest sock out there.