All I wear are birks ... I have feet, knee, and back problems and although they still bother me, they bother me much less with the wearing of birks. Over the years, I've managed to acquire 6 or 7 pairs of them ... usually wear one main pair which are 2 strap but the straps are a bit thinner and more feminine looking that the classic two-strap birks and they are a black patent leather. I also have some goldish ones that are the same style, some red summer sandles that are 2 strap and thin straps, but both straps go across the area just above my toes. I do know that you can get the liner from Birks that will fit into other shoes. I've bought all of mine from QVC or Ebay ... you just need to know what your european size is and that they don't sell Birks in 1/2 sizes so you go up to the next size ... I wear a size 8 1/2 usually so my birks are a size 39 european or 9 american sizing ... on ebay they will often list under both sizes. Good hunting/shopping!