HOW THIS SUN DETECTION PATCH WORKS Each SunPatch sticker is crafted with a natural, UV-sensitive ink that turns purple when it's time to reapply sunblock. Placing one of these sunscreen reminder stickers on your kiddo’s skin will help prevent sunburns and sun damage! We’ve used medical-grade, water-resistant adhesive so this sun-safety patch stays put. Peel off, replace sunscreen, and slap on a new sticker! These sunscreen dots are perfect for babies, kids, and even older family members who still think SPF is optional!