NT501  
     *    Subminiature volume: 51.5 x 29 x 17mm
*       Frequency: 58KHZ or 8.2MHZ for option
*        Alarm Sound: ≥95db±5%.
*        Dual alarm function
*        Standby time over 2 years
*        Normal or Super lock for option
*        Light and Sounds indication for switch on/off
*        Low battery indication
2A
 
  