Batteries die quickly in my GoPro cameras. Wasabi Power's handy kit comes with 2 extra batteries and a wall wart.
I get around 1 hour of recording from a single battery, based on the settings our video editor Eric recommends. On a typical dive day of scuba diving I need several batteries, and if I am on a trip I'll need to recharge them again for the next day. This kit has me covered. GoPro ridiculously expects you to charge via the camera's USB. It takes forever.
There is also an adaptor for charging in your car. I have not used it.