Lovely hat. Includes pre-installed battery and a spare. The power supply tucks into the back of the hat behind the brim and has a tiny on/off switch. I was fretted the hat would look weird when the lights aren't on, but it's excellent as is.
I LIKE this hat! I was stressed over the quality of fabric but it seems exceptional. I've bought some previously that were actually too slim and just seemed like it would tear up quite easily. This hat went beyond my hopes. I like the lights too. It's extremely adorable. I got one for an upcoming event and my children are fighting me for it I'll be purchasing more for my kids and to give as Xmas gifts.