I love Birkenstock shoes because of the comfort and have worn them since the 80's.  This pair had to be returned because they sent me the wrong size. I have several other Sidney style and I love them.  I wear them all day and every day of the spring, summer, and fall. When the snow flies then I have to wear something different. I also wear the Arizona, Florida, and Orlando. I own probably 16 pair and they are all 36 M (called regular width) and they sent me 36 N (narrow).