I sometimes wear a custom or store-bought orthotic, so I ordered a 10M, although I usually wear a 9 1/2 N, (though usually a 10N in Clark's Artisan line).  Fit was great - roomy enough for thick socks and/or othotic, if needed, but not so loose as to slip or rub.  The boot has excellent support, however, so I probably won't be using the insert.  Looks very-well made and attractive.  Haven't worn it long enough to assess durability.