Once your hair is wet and prepped, the work truly begins. That's when you need to get your curls from drenched to dry, or run the risk of water — and product — seeping from your hair, ruining your fresh T-shirt, and still feeling damp when lunchtime rolls around. For some, air-drying is ideal, but for others, hours of time between wet and dry hair isn't. But the right diffuser will give you defined, perfectly-dried hair without the damage or disruption of your curl pattern (and, with it, frizz).