These shoes fit perfectly until I walk, giving significant up and down slippage in the heel.  I measure 6.5 on the line, so 6.5 to 7 W is my usual range.  I sometimes risk 7 Ms, and these proved adequately wide across the front.  Because of the lining, I don't think heel no-slip stick-ons will help.  I will have to wear them a while to figure out if they will be adaptable to wearing long-term outdoors.  At the minimum, they will be great indoor slippers.  Cozy and nice-looking.