Many people do not know when they should re-apply sunscreen lotion. To solve this problem, a gadget has been introduced which will tell you that it is time to apply sunscreen lotion. Buy UV Sun Sense Wristbands, with $9.99 for a pack of seven. Just apply sunscreen with SPF 15 or higher and wear the wristband before going outdoors, and the orange band turns purple as soon as it’s exposed to the sun. When the wristband turns brown, signaling its time to reapply. After the skin experiences maximum level of safe sun exposure, the band turns salmon, which signifies it is time to beat it indoors. Doris Day, clinical assistant professor of dermatology at New York University Medical Center, says yes. “I think that if people use them as a reminder to apply and reapply sunscreen, to wear sun protective clothing, and to stay in the shade when possible, they serve as an excellent tool to help keep people safe while out in the sun.”