I bought this for travelling so I don't have to bring my full size hairdryer and diffuser. I was hoping it would fit the hotel hairdryer, but was a bit worried based on reviews that said it didn't fit. For my purposes, it worked very well. It fit the hotel hairdryer just fine, but I could see how some of those older hotels that use hairdryers with a larger end could be a struggle. It is rubber/silicon, so it could stretch in theory, but it may take a lot of work to get it on. I love that it collapses nearly flat for packing, although during drying it did collapse on occasion if I pushed near my head. So that took some adjustment in how I dry my hair. All in all, I'm very pleased.

UPDATE: It kept collapsing, so I ended up buying another one that is SO much better. I'd recommend the Hairizone-Universal-Diffuser-Adaptable-D-1-7-Inch instead. This one is great in terms of packing, but for actual use, it just isn't the same. It was a fight with it to keep it from collapsing every two minutes.

Occasionally the diffuser would collapse while drying my hair.

The diffuser is lightweight and collapsible, so it is fairly compact for travel or for storing at home. I did struggle a bit getting it onto my hairdryer initially, but I simply warmed up the diffuser attachment with my dryer and then it was flexible enough to attach to the nozzle of my dryer. It works very well, I am happy with this purchase.

Great product. Exactly what I was looking for.