Feature: 1. Flexible Application: Package contains 4 doorbell system units, 2 indoor and 2 outdoor, allowing switching between ring call and intercom modes. This intercom system is suitable for hospitals, hotels, factories, teahouses and other scenes. 2. Indicator Light: Humanised design with intercom and power indicator light, this wireless intercom doorbell provides users with clear visual cues, easy to operate for anyone. 3. Remote Transmission: The wireless intercom system has a transmission distance of up to 1000 meters in open areas and 20 to 50 meters through walls, ensuring practicality. 4. Adjustable Function: Portable intercom system with 2 channels, A and B, 3 volume levels, allowing users to customize settings according to their preferences. 5. Long Standby Time: The walkie talkie can operate for up to 48 hours on a single charge. To ensure uninterrupted use, it is recommended to charge the walkie talkie every two days. Specification: Item Type: 2 Way Voice Intercom Material: ABS Waterproof Level: IP54 Battery: Inner Unit: Rechargeable Lithium Battery 3.7V 1800mAh x 1 (with built in battery for shipment) Outer Unit: Rechargeable Lithium Battery 3.7V 1800mAh x 1 (with built in battery for shipment) Application: Widely used in home, office, laboratory environments, medical facilities, etc. Basic Parameters: Working Temperature: -20°C to 55°C Transmission Distance: Open field 1000m / 3280.8ft; Through walls 20 - 50m / 65.6 - 164ft Operating Frequency: 410MHz to 490MHz Sound Adjustment: Three adjustable levels. Package List: 2 x Indoor Unit 2 x Outdoor Unit 2 x Base 2 x Data Cable 2 x DC Power Cable 1 x User Manual 1 x Sticker 1 x Screwdriver