Everytime you put your little ones in a car seat, you can clip one end of Elli to the seat and the other end to driver side door. When you arrive at your destination, Elli is there to remind you to take a look behind you.
Our hope is that Elli will give every drive a happy ending. Or, at least, prevent a sad ending. Even when you are fully aware of your surroundings, please take a look behind you.
Elli's design is free. In fact, it is more than free; it is open-sourced under MIT license.