This is a multifunctional product, specially designed for bicycles and simple electric vehicles Waterproof design life, can be used at any time. outdoor in rainy days, easy to clean. install and use and very convenient in function Four switches control 4 siren tones and 4 ring tones are freely selectable The 6 LED lights will flash along with the bell ringing, especially when there is not enough light Power Source:Two size 5 AA batteries (not included)