the first 10 years i weny,i used to get a couple hundred sand flea bites on my ankles.then i decided to give the flea collers a try,and they worked awsome.not one sand flea bite at all.so the last 22 years ive used them,and recomend them highly.do not put them on tight though.leave enough room so they slide up and down your leg.leave them on in the water so it washes off.i put them on when i get there and take them off when i leave.i also sleep with them on.if they dont slide up and down your leg,you will get a rash,so leave them loose and have a great time in jamaica.