Door Chime, Door Sensor Chime for Door Opens – Door Ringer with 500ft Operating Range 52 Chime Adjustable Volume Mute Mode LED Indicators –Entry Alert Chime for Business/Home/Office;

This door open alarm for home/business/office /retail store /kids installs tool-free to nearly any
  door or window to notify you of any unwanted entry. The wireless and portable design allow you
  to install the wireless door entry alert in any section of your home, or business.
 
  Expandable (up to door sensor 40pcs)
  You can choose one for the front door and a different one for the back door. Then you will be able
  to distinguish which door is being opened.
 
  LED Indicator for the Hearing Impaired )
  Secrui entrance alert/ Exit alarm features a LED indicator that creates a visual LED alert, allowing
  the hearing impaired to take advantage of the system.
 
  Parameters of Doorbell Receiver:
  52 tones optional
  Colorful LED indicator
  Standby current :<3mA Working current:<11mA
  Volume Range: 0~110dB 
  Radio frequency:433MHz
  Receiver Size: 4.5x2.3x1.7in
  Working Voltage: 110V~240V,50-60Hz AC
  Operation range:400ft (in open area)
 
  Parameters of Door Sensor: 
  Non-waterproof
  Working Humidity: ≤ 85%
  Transmitter Size: 3.0x1.0x0.60in
  Working temperature: -4°F~122°F
  Working range: 400 ft (in open area)
  Expandable door sensors: < up to 40 
  Working current: 3uA(standby), 15mA(Transmitting) 
 
  Tip:Ensure the distance between door sensor and magnet part not exceed 0.4inch
If you still have questions about the open door window alarm for home security,please contact
with our customer service team to get more information .

Package:  
  1* Secrui Doorbell Receiver 
  2 *Secrui Magnetic Door Sensor(battery -included) 
  1 * User Manual