In "So Totally Versailles!" Clover says that not only does the Incredi Shrink Compact Hair Dryer make them totally "cute size", it also seriously refreshes the hair.
Goof: The dryer is shown shrinking in size when Samantha uses it on herself. When she is down to doll size, the gadget is also shrunken down to her scale. As no one used a resizing ray on the actual gadget (and it did not shrink when Sam used it to shrink Clover and Alexandra moments before) it should have remained its original size. It was likely shrunken so that the girls would not struggle in trying to carry it around in their shrunken state.