The criterion of the redesign was to prevent the patient from overdosing or overusing the inhaler. In order to do so, HS Design developed a feature in which upon removal of the cap, the device was cocked; followed by patient inhalation. In order to actuate the unit again, the cap must be repositioned; thus preventing patients from double-dosing. The built in counter counted down to create the internal reaction that produced the vapor. The lock-out feature was key to the design success.