Features: With infrared sensing, it enjoys strong sensitivity, unaffected by light. Rotating bracket makes it easier to adjust monitoring angle. Built-in speaker for welcome loudness: 85±5 decibels. Powered by 3* AA batteries, it is energy-saving and durable (batteries not included). Boasting long-distance detection: 0-3m. Installation and use method: 1. Open the battery cover according to the direction of the arrow, load 3* AA batteries (alkaline batteries are recommended), and then cover the battery cover. 2. Turn the doorbell switch to the voice or alarm file. 3. When a guest enters, the electronic welcome doorbell will make the sound you have selected before. Specification: Condition: 100% Brand New Material: ABS Power Supply: 3* AA(Batteries not included) Color: Milky Size: Approx.9*6.5*3.5cm / 3.54*2.56*1.38in Package List: 1* Doorbell 1* Bracket 1* Ball Joint Notice: 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. 2.Sensitivity and volume have been set to standard state, not adjustable. 3.If the product has an automatic sound or abnormality, please check the battery power supply or the installation position. (Avoid directly facing the illuminating light / sunlight / reflection / direct exposure.) If temperature is too high (above 30 degrees) detection The detection distance will be from far to near, which is normal. 4.When the doorbell sound is weak, please replace the battery. It should not be installed in a position where the air flow changes greatly (such as: air outlet, exhaust fan, electric furnace, etc.). 5.Do not install in the sun and rain. local. 6.Please understand that colors may exist chromatic aberration as the different placement of pictures. 7. Please allow 1-3cm error due to manual measurement and make sure you do not mind before ordering. 1、With infrared sensing, it enjoys strong sensitivity, unaffected by light. 2、Rotating bracket makes it easier to adjust monitoring angle. 3、Built-in speaker for welcome loudness: 85±5 decibels. 4、Powered by 3* AA batteries, it is energy-saving and durable (batteries not included). 5、Boasting long-distance detection: 0-3m.