Function: A loud siren that draws people's attention to the street. Protect your children from danger by warning them or noticing others. A switch controls the flash modes that cause flicker. Easy to attach to your bike. Mounting loop fits 28-30 mm internal diameter pipe. Description: Material: ABS plastic; Electronic Components LED Color: RED and Blue Power: AA Battery X 2 (not included) 4 Audible siren sound. 6 Red blue led light with bicycle sirens. Contents: 1 X Bicycle Bell