These earrings are based on some similar light-up earrings that were sold in the 80's. This upgraded version has LED's, a micro-controller and is powered by 2 small hearing aid batteries. There is even an on/off switch on the back to turn off the lights while not in use. The micro-controller is programmed to fade the LED's randomly at different speeds. Feel free to contact me for custom color and LED size options. These are made to order, so can be personalized. Diameter dimension: 44mm (1-3/4") Weight with batteries: 6.5 gram (0.23 oz) Micro-Controller: ATtiny202 Batteries: 2x size A13 zinc-air hearing aid batteries Battery life: up to 100 hours