Color changes when fever rises Cooling gel sheet Weakly acidic, menthol scent Cooling lasts for 10 hours Small size, 16 sheets (2 sheets x 8 packs) Size: Approximately 4cm x 11cm For sudden fever / For heatstroke prevention / For restless nights / For cooling after sports The color gradually changes to pink when the temperature rises to 37.5°C or higher. The color returns to the original purple when the temperature drops below 37°C. * The appearance when applied is white. * This product is not a medicine. A certain famous sheet has an expiration date, but this one does not. The manufacturing date is October 20, 2020. I think you can use it without any problems, but please refrain from purchasing if you are concerned. The contents will be taken out of the box, and the box will be folded and enclosed.