Mine are the white version which are the -40F, I belive the black version are only -20F.

Love them - look stupid and dorky but WARM. Only thing better would be a pair of mutluks, but they are expensive and not water proof (overflow can be a major issue.)

edit:
I stand corrected -60F
http://www.armysurpluswarehouse.com/white-mickey-mouse-or-bunny-boot-with-valve.html