These are great bike lights as they tell you how much of a charge you still have, so you know when to take it off your bike and charge before your next ride! Comes with a back light and they are so easy to take on and off(no screws required). We now have 3 for our 3 bikes when my kids and I go biking at dusk! Thr back light has 3 modes of lights…solid, flashing and up and down. We usually put it on solid as flashing might bother some drivers or other cycylists.