Twisthaler is multi-dose Dry Powder Inhaler (DPI) device. It delivers the measured dose of the medicine into the small airways of the lungs in the form of fine powder. The inhaled medicine is used as maintenance treatment that helps prevent and control asthma symptoms. It is a breath actuated inhaler. That means there are no pressable buttons to release the dose instead you just have to breathe in quickly and deeply to use it.