Features: 1.The detector is super sensitive, not reporting false alarms. It can plug in or use battery. 2.Fully automatic infrared sensing, with strong sensitivity, can not be affected by light. So the doorbell can be sensed during day and night. 3.The swivel bracket makes it easier to adjust the monitoring angle. You can place it anywhere or fix it on the wall. 4.The built-in speaker of the host has a welcome loudness of 855 decibels, which is the loudest in the welcome family. 5.16 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). Specification: Features:_x000D_ _x000D_ The detector is super sensitive, not reporting false alarms. It can plug in or use battery. _x000D_ Fully automatic infrared sensing, with strong sensitivity, can not be affected by light. So the doorbell can be sensed during day and night. _x000D_ The swivel bracket makes it easier to adjust the monitoring angle. You can place it anywhere or fix it on the wall. _x000D_ The built-in speaker of the host has a welcome loudness of 855 decibels, which is the loudest in the welcome family. _x000D_ 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). _x000D_ Powered by 3 AA batteries, it is energy-saving and durable in use. (This unit does not include batteries). _x000D_ Remote detection can reach to 0-6 meters, and the available temperature is 0-25 degrees. _x000D_ Widely suitable for shops, warehouses, office buildings, factories, and homes. _x000D_ _x000D_ Specification:_x000D_ Color: White_x000D_ Material: ABS plastic_x000D_ Sound:_x000D_ The first Level: Welcome_x000D_ The Second Level: Dingdong +16 music + alarm sound (adjustable)_x000D_ Battery: 3 AA batteries (not included)_x000D_ Remote Detection: 0-6 meters _x000D_ Applicable Temperature: 0-25_x000D_ Installation and Use Method:_x000D_ 1. Push the battery cover on the back of the doorbell in the direction of the arrow, install 3 AA batteries (alkaline batteries are recommended) and cover the battery cover._x000D_ 2. Turn the doorbell switch to the voice or alarm level._x000D_ 3. When a guest enters, the welcome doorbell will sound what you have chosen before._x000D_ _x000D_ Package List:_x000D_ 1 x Welcome Sensor _x000D_ 2 x Base_x000D_ _x000D_ Note:_x000D_ 1.Each time the battery is installed, the product needs to be self-tested for about 15-20S, and then enter the normal working state._x000D_ 2.Sensitivity and volume have been set in standard state, not adjustable._x000D_ 3.If the product has an automatic sound or abnormality, please check the battery power supply or the installation position is correct._x000D_ 4.Avoid directly facing the illuminating light / sunlight / reflection / direct exposure, if the ambient temperature is too high (above 30 degrees), the device will appear from far to near, which is in normal._x000D_ 5.When the doorbell sound is weak, please replace the battery. The doorbell should be installed in a position where the direct air flow changes greatly (such as air outlet, exhaust fan, electric furnace, etc.), not installed in the sun or rain.