Truly bliss to sleep with these wonderful booties. I nearly burst with excitement when I slipped them on for the first time, so silky, so poofy, so... Purple! Nothing ruins a night sleep for me like ice cold feet. Never again. There is little to no chance that my feet will ever get cold with these on! I have tested them down to -5 F now with my winter sleep setup (a 20 degree ENIGMA inside of a 40 degree CONVERT) Toasty as pie all night long!!! Easily my biggest sleeping issue is now solved at a mere 2 oz. weight penalty this is totally worth it to me. thanks EE crew!