Feature: 1. Versatile Communication: This set of wireless intercom doorbells come with two receivers that can be used as an intercom system or can be turned off with the mute mode for silent use indoors. 2. Expandable System: The intercom doorbells can be easily expandable to work with nearly any indoor or outdoor system. 3. Anti Interference: The doorbell adopts FM wireless intercom and is not affected by WiFi interference and does not interfere with other smart devices. 4. Easy to Use: The intercom function is activated with a push to talk button and features volume and channel selection. 5. Waterproof: The outdoor unit is waterproof with cap design, and designed with a charging indicator light that turns green once charging is completed. Specification: Item Type: Wireless Intercom DoorbellsMaterial: ABSCharging Base: 12V-450mAh Intercom: Intercom Key SET: The External Unit Is Not Functional VOL: Volume Selection CH: Channel Selection Waterproof Cover: Outdoor Waterproof Charging Indicator: Red (Charging) Green (Complete) Outside and Inside Door Machine Battery: 2500mah 18650 Lithium Battery (Built In) . Package List: 1 x Outdoor Unit1 x Indoor Unit1 x Outdoor Unit Base1 x Charging Base1 x Charging Cable1 x Manual1 x Pack of Screw2 x Sticker