These heel grips are very useful. They've very sticky, so they dont slip out of your shoes and make you look stupid with a cream thing pokeing out the back of your shoe. They are very comfortable, and i would recommend someone to use them even when shoes are not that much bigger. I would say that for the use of making shoes a little smaller, they probably only work about a half size, so you would have to add an insolve to make them roughly a size smaller too. They are great for making work shoes more comfortable, as i said, even if they arent being used to make shoes smaller. Particularly good for court shoes with heels, which tend to slip off without a strap on and they tend to mould to the back of your ankle which make them more comfortable. They're a must-try if you require your shoes to be better fitting.