Got these as a gift for my husband.  He likes that they feel like a shoe as they are leather, have some arch support,and a rubber sole.  The lambswool lining is warm, but it breathes and is not hot or sweaty.  He wears a size 12 medium width shoe, and the 12 fits him well.  He works from home, and wears these all day.  I just ordered a 2nd pair.  Very happy with them!