I was looking for decent eyewear retainers for my reading glasses, but came across this and thought it would be great for my sunglasses. These work extremely well and as advertised. They mounted very easily, but securely to my sunglasses and it's great to know your glasses are secure but you don't have to have a chord or chain sitting on the back of your neck all day in order to achieve it. I have a rather large sized head and size is not an issue.