Feature:1. Portable Doorbell Unit: This package includes 4 doorbell system units, 2 indoor and 2 outdoor, which can be switched between ringtone call and intercom mode.2. Intuitive Indicator Lights: The system features a humanized design with intercom and power indicator lights, providing users with clear visual cues.3. Long Transfer Range: The intercom system boasts an impressive transfer distance, reaching 1000 meters in open areas, and 2050 meters through walls, offering high practicality.4. Adjustable Functionality: This portable intercom system comes with 2 channels, A and B, and 3 volume levels, allowing users to customize settings according to their preferences.5. Reliable and Long Lasting: Stay connected with a single charge lasting up to 48 hours, ensuring continuous use with only one charge every two days.6. Versatile Application: This clear sound intercom system is widely applicable to various scenarios, including hospitals, hotels, factories, teahouses, and more.Specification:Item Type: Wireless Intercom System Material: ABSWaterproof Level: IP54Battery: Indoor Unit: Rechargeable Lithium Battery 3.7V 1800mAh x 1 (Shipped with Built in Battery)Outdoor Unit: Rechargeable Lithium Battery 3.7V 1800mAh x 1 (Shipped with Built in Battery)Application: Widely used in home, office, laboratory environment, hospitals, etc.Basic Parameters:Working Temperature: -20-55Transmission Distance: Open space 1000m, through wall 20-50mWorking Frequency: 410M - 490MSound Adjustment: Three levels adjustable.Package List:2 x Indoor Unit2 x Outdoor Unit2 x Base2 x Data Cable2 x DC Power Cable1 x User Manual1 x Sticker1 x Screwdriver