Hair Dryer Diffuser Type: Diffuser Color: Black Shape: Round Material: Plastic Inner Diameter: Approximately 5.5cm Outer Diameter: Approximately 13cm I have never used this since I purchased it, and it has been stored at home. I think it can be attached to most standard hair dryers. (I was able to attach it to my hair dryer, which has a 5.5cm diameter nozzle.) I am offering this for sale, hoping someone will use it. Please understand that shipping costs will be higher due to the height of the item.