these are wool and it's true, you don't sweat in them, hot or cold. They have wool bottom also which is very hard to find, most all slippers have a hard sole to wear outside but I wanted these to not wear outside. We have new carpet so I put these on when I get home and the wool never tracks any dirt onto the new carpet. Very comfy too. I wouldn't mind a few more styles, which they have a few but never in my size 8 which is pretty common. But they probably will next winter. Try them if you want a total indoor slipper that you never sweat in.