Luckily I had two dryers because the diffuser would not fit the one with a large nozzle. It does stretch a bit, but it does not fit all size dryers. I had to stretch it more to even fit my dryer with a much smaller nozzle. So, after figuring out how to attach the diffuser to the dryer, I made an attempt to diffuse my hair. It was an unsuccessful attempt mainly because I could not make it stop collapsing. I'm not sure whether or not it has a latch or something to make it stay in place, but I was unable to do so. It would not stay up so I gave up!! Therefore, I cannot say how effective or efficient the diffuser was, but I can say that it is definitely collapsible and with that is easily stored.
I received this item for free in exchange for my honest opinion.