The right choice between a flat iron and a straightening brush depends on what your goals are with your hair. If you want to remove as much volume as possible, a flat iron will do the trick, and it may work more quickly, too. But a straightener brush is the better option for being able to keep the volume your hair naturally has and for adding more volume to it. That makes it an ideal choice for anyone with fine or thin hair or for people with thicker hair who want to be able to keep their hair’s natural thickness while straightening it.