The Thule Delight adds visibility and safety to the back of your rear-mounted Thule child bike seats, Thule bike trailers, and Thule multisport trailers. The Delight has a unique mounting clip thats quick and easy to install. It uses internal LED lights that are bright and last a long time on a set of batteries. The Delight also has a LED Battery indicator, so you'll always know how much battery life you have left.It requires two AA batteries (not included) for operation. The Thule Delight is the perfect device to add additional safety measures to those sunset and early evening bike rides.