Special manufacturer in siren, please contact us to get more information Function feature: 1. It conform with national standard GB108-1999. 2. Novelty structure, attractive design, excellent, excellent performance, complete function, covenient operation. 3. Monolithic Integrated circuit in steadier performance. 4. Special super-thin design, harmonious with inner decoration. 5. Kinds of warning tone are optional such as siren, horm, tool, base tone and amplifier tone. 6. Volume of amplefier tone and warning tone are adjusted ar your option. 7. Front panel are shown in Chinese or English. 8. Controlling two groups of big power light bar at the same time without being restricted by power switch of siren.