Bought these for my husband & he loves them.  He said he usually wears size 11 shoe & size 11.5 in boots.  I bought the 11.5 & they fit perfectly.

The first day he had them, he hiked for 2 hours w/ our dogs in a local park w/ fairly rough terrain.  He reported no blisters & extreme comfort.  After wearing them the entire day he said they were so comfortable he didn't want to take them off!  He also said they didn't make his feet hot:)