9V DC from a walkie talkie charger. I have the charger paralell with a set of alligator clips. I got the same brilliance on a 9V battery, I was looking direct top center, they'll work well for the porch flashers I make for people. They use em for panick situations we also have a few elderly neighbors my parents look after, I put em in and control em with a transmitter and receiver using the Normally open on the receiver in case something happens and they cant get to a phone, older people wont buy cell phones, drives us all nuts.