Estiq New Police 4-Melody Bicycle Power Horn Siren, 6-LED Strobe Blue and Red Bicycle Safety Light MUST READ: There is a control key at the BOTTOM of TOTAL CONTROL BOX, when it's "ON" position, light brights all the time. When "OFF" position, light only brights when pressing the one of 4 buttons. 4 Button Controls: Four buttons control 4 tone of police whistle. When press button bike light emits a 6 Red and Blue LED Light with the effect of flicker and the police whistle. Practical, Reliable, and Durable. Simple to install - Mount this bike rear light anywhere you want in seconds, such as the handlebar, the seat post or anywhere on the frame. Can be used for a wide range of activities: road biking, city commuting, hybrid bikes, kids bikes. Keep your kid from danger by warning or noticing others. Dazzle and Brilliant Bicycle Light. Very easy to install on your bike. Perfect present for your kids. Operated by 2 AA batteries (Not Include).