Lights on both sides light up with a button on the inside. Independent buttons. Lights tested on both sides, but one pair of batteries is dead (swapped to test). Uses CR 1220 3V Batteries and I don't have a replacement set. Both sides do work though. This pair of sunglasses features everyone's favorite Disney character, Minnie Mouse, and boasts a unique light-up feature that is sure to turn heads. The frame is a cute shade of pink and adorned with pretty flowers, perfect for any little girl who wants to add some fun to her outfit. The lenses are a classic black and the temple length measures 114 mm. This item is perfect for any young girl looking to add some personality to her wardrobe. With its light-up feature and adorable Minnie Mouse design, these sunglasses are sure to become a favorite accessory. Whether worn on a sunny day or just for fun, these sunglasses are a must-have for any Minnie Mouse fan. ? I COMBINE SHIPPING ? ? 60 day, no questions asked return policy. ? ?As a TOP RATED PLUS seller, I provide some of the best customer service and satisfaction .? I pack all orders with great care and provide next day shipping to ensure safe and timely arrival of your goods. Electronics are shipped without batteries unless otherwise noted. If something arrives and is not to your satisfaction, please let me know and I will make it right. Customer service is my highest priority. I like to give fast and positive feedback and try to do so upon receipt of payment. Thank you for your business! You are very much appreciated.