The LIMITmarker® F-B is a single-use indicator that provides an easy-to-read, irreversible visual signal when there has been exposure to a temperature above the threshold limit. LIMITmarker technology is based on the precise melting of heat-fusible materials at specified temperatures.

When the indicator temperature remains at or below 16.5°C, the small window in the blue rectangle remains white (Fig. 1).

When exposed to temperatures at and above 18.5°C for 2 hours or less, the white window becomes pink or red (Fig. 1). The appearance of any pink or red in the window means that the indicator has reached endpoint.