No battery require. It Power from a USB Port. No need to press button to turn it on. It switch on automatically soon as you turn on your ignition. It come with USB to Car 12V adapter. It come with a 2GB pre-loaded pay as you go sim card. You can even use this at home or office!
Amazon selling these for £48.99.
also if you happen to have one of these free 100GB EE sim cards then you can use this with it.