Perfect addition to your car, bike or bicycle. Motion activated, lights automatically when the vehicle moves. Easy installment, simply screw it onto the tire valve. Super bright, energy saving and long lifespan LED. Perfect for safety at night time and bad weather. Material: Durable metal and plastic. Powered by 3 replaceable AG10 button batteries (Included). Length: Approx. 2.4" x 6.2 cm. LED Light Color: Blue, Green Choose The Color you want.