Caution!!<br />I've owned the Kayano 17,18, and four pairs of the 19.  All great shoes. The 21 fits nothing like the others because it is a lot more narrow.  It's a well cushioned shoe but so narrow that it is uncomfortable,  Unfortunatley it's not something that just loosening the laces will correct.  I cannot recommend the 21 without first trying them.  THEY FIT NOTHING LIKE PREVIOUS KAYANOS