Place of Origin: Guangdong, China (Mainland) Brand Name: Saful Model Number: TS-5513 Usage: signal amplifier Transmission frequency: 433 / 868 MHZ optional Working Power: DC12V Distance can be extended: ≥30M Operating temperature: -30 to +40 degree Backup Battery: 3.7V / 800mA Lithium battery Charge Time: ≥12 hours color: white service: OEM, or ODM certificate: CE,FCC,ROHS http://www.doorbellalarm.com/