The detector is super sensitive and signals no false alarms. It can be connected to a power outlet or powered by battery. The fully automatic infrared detection, with its high sensitivity, is not affected by light. Thus, the doorbell can be detected day and night. The swivel bracket makes it easy to adjust the monitoring angle. You can place it anywhere or mount it on the wall. Infrared ringtones (available day and night) are divided into two levels. The first level is a welcome signal and the second is a \"ding-dong\" with 16 music and alarm sounds (adjustable). Powered by 3 AA batteries, it is energy efficient and durable. (This unit does not include batteries.) The detection range can reach 0 to 6 meters, and the available temperature range is 0 to 25 degrees Celsius. Excellent for shops, warehouses, office buildings, factories, and homes. Specification: Color: White Material: ABS plastic Sound: First level: Welcome Second level: Dingdong + 16 melodies + alarm sound (adjustable) Battery: 3 AA batteries (not included) Remote detection: 0-6 meters Applicable temperature: 0-25°C Installation and operation method: 1. Push the battery cover on the back of the doorbell in the direction of the arrow, insert 3 AA batteries (alkaline batteries are recommended) and replace the battery cover. 2. Turn the battery cover. Turn the doorbell switch to voice or alarm level. 3. When a guest enters, the welcome doorbell will emit the tone you have chosen. Package list: 1 x Welcome sensor 2 x Mounting brackets Note: 1. Each time the battery is installed, the product should self-test for about 15 to 20 seconds before entering normal operating mode. 2. Sensitivity and volume have been set to default mode, no