Feature: 1. Dual Receivers Work Simultaneously: With two receivers, you can simply install two doorbell devices in different locations for all round monitoring. 2. Sensitive Sensing Design: With an efficient and sensitive sensor, our doorbell automatically triggers the doorbell without pressing the switch, and not affected by light. 3. Voice Prompt: When someone approaches the door of your store, the built in voice module will emit a ding dong sound to remind you that a customer has visited. 4. Powerful Alarm function: In addition to the doorbell beep, the device also has an adjustable alarm sound to give a stronger warning of potential threats. 5. Flexible and Easy Installation: Thanks to the wireless design, you can install the doorbell indoors or outdoors as needed, providing more installation options. Specification: Item Type: Infrared Sensor DoorbellMaterial: ABS Transmitter: Battery Type: Lithium battery Battery Model: AAA battery x3 (Shipped without batteries)Size: Receiver: Approx. 80 x 76mm / 3.1 x 3in Transmitter: Approx. 80 x 59mm / 3.1 x 2.3in . Package List: 1 x Transmitter 2 x Receiver 1 x Connector1 x Base 2 x Screw 2 x Expansion Screw1 x English Manual