Z ZICOME 10 Pack Light Up Fiber Optic Led Hair Lights - Multicolor Flashing Barettes - Party Supplies Set of 10,Rainbow Colors (Alternating Multicolors),batteries included and installed. Easy to hide under your hair but can glow with many colors You can wear them again and again. Just change the batteries when Glow become too dim,Uses two CR1220 replaceable batteries(included),you can get them at most drug, electronic, or hardware stores. Approximately 80 fiber optic fibers cut at variable lengths from 5 inches to 14 inches long Great for any nighttime event - rave party, prom, holidays, parties, nightlife, concerts, raves, festivals, weddings, they add sparkle to a floral arrangement or table centerpiece, and more!