I usually get a wide size, but reviews said the 'B' width was wide.  Although they fit 'snugly' they are not too tight. (besides being adjustable and stretchy across the top).  There is arch support - but not a great deal.  More support than a 'flip-flop' or any flat soled shoe.  They are VERY light.  I wear them with socks.  The few times I wore them without socks, my feet made loud noises (embarrassed myself!).  I do not wear these in public because wearing socks with sandals is not acceptable - not sure why, but it's not. :(