I applied these to a pair of Serengeti sunglasses that I had stored away hoping to be able to use them again. This product made that possible!I made the mistake of attempting to cut the semi-circle side when cutting down the first pair which resulted in lenses that were narrower than the original product. I also used too much pressure when applying which created blurry spots. I was still able to do my job (deliver mail accurately) using my first attempt.Last night I tried again with the 2nd set. I trimmed straight across the bottom of the semi-circle just enough to fit my sunglasses and get the top of the bifocal lens in the correct placement. I also used very little pressure (just enough to spread the single water drop to every edge of the lens) and made sure to not push or slide the lens for placement (if it’s not in the right place, lift it and try again!)Today, perfect reading vision!!I have used stick on lenses before that worked well. I applied as instructed but vision was blurry. I thought maybe I ordered wrong strength so done checked my regular glasses were indeed 2.0 and these were as well.These glasses I applied to were cleaned and high end. Still blurry. ?I will try on 2nd pair to confirm but 1st impression was not great.I tried these on two pair of sunglesses. Could only see clearly through a couple of spots. There were no air bubbles and product was installed per instructions.Great itemBlurry, couldn't use. Wasted moneyToo thick, too noticeable, couldn’t get them in the right place or something because they were ultimately blurry. I threw them out. Expected a lot better at this price.don't buy this product they came off few minutes after i put them on plus they are not very clear