Abbott FreeStyle Libre 2 sensor for continuous glucose monitoring. New sealed box. The FreeStyle Libre 2 sensor lasts 14 days and requires a FreeStyle Libre 2 reader or a compatible smartphone in order to work. Most smartphones work! Optional, real-time glucose alarms* notify you when you are low or high. Unsurpassed 14 day accuracy for adults and children with diabetes (ages 4 and older). Easiest iCGM sensor to apply** with no in-person training required.