The detector is super sensitive, not reporting false alarms. It can plug in or use battery. Fully automatic infrared sensing, with strong sensitivity, can not be affected by light. So the doorbell can be sensed during day and night. The swivel bracket makes it easier to adjust the monitoring angle. You can place it anywhere or fix it on the wall. The built-in speaker of the host has a welcome loudness of 85±5 decibels, which is the loudest in the welcome family. 16 music infrared welcomes(available in day and night) has two levels. The first level is welcome, and the second is dingdong & 16 music & alarm sound (adjustable). Widely suitable for shops, warehouses, office buildings, factories, and homes. Powered by 3 AA batteries, it is energy-saving and durable in use. (This unit does not include batteries). Remote detection can reach to 0-6 meters, and the available temperature is 0-25 degrees., Manufacturer: Dioche