I don’t know the longevity, but I use them. At my place there are thousands upon thousands of photos never accessioned, still in albums or stapled (yes, stapled) to cardboard. And because of their cost, I decided to use them. My only complaint–not that it’s really that–is that they’re not totally transparent, so to scan or view them, they must be removed. But they are an economical solution. As I said, I know nothing about their longevity.