I sleep in mine and they have never fallen off! Highly recommend . I was able to walk all over Charleston, SC in 100 degree weather with these sandals. I really dont understand why some of the Birkis are discontinued , they are great. 5 inches and pretty small and skinny. They made well, light weight, evidently comfortable & easy to run & play in. Fits perfectly, exceeded expectation He wears it around the house and sometimes in the backyard. Will have to pass them onto someone with like size 3 feet It favors the treble frequencies to a degree that makes the speaker sound a trifle "thin" only in A-B comparisons.