I used it for less than 3 years and the battery is wearing off. It will act weird after 10 miles, so I recommend bring the charger with you just in case. Not very often, it will stop on its own. Just slap it several times and it will go back to normal.

Description from the website:
Built-In Front LED Lights
12.4 mph Max Speed
12.4 Miles Range

I have M size helmet and a lock available for extra 15 bucks