Item Type: Wireless Voice Intercom Doorbell Material: ABS Model: H9 Battery: Outdoor Unit: Rechargeable lithium battery 3.7V 1000mAh (built in) Use: Widely used in household, office, laboratory environment, medical treatment, etc. Basic Parameters: Working Temperature: -20 to 55 Transmission Distance: Open Area: 100 meters; Through Wall: 5-20 meters Package List 2 x Indoor Units 1 x Outdoor Unit 1 x USB Cable 1 x Screwdriver 1 x User Manual 1[Intercom Kit] This intercom doorbell kit includes one outdoor unit and two indoor units for internal call and 2 way calls. Perfect for use in home, hospital, and other places. 2[Dual Mode Operation] The two indoor units can be switched between doorbell ring mode and intercom mode, providing flexibility for communication needs. 3[Power Saving] The outdoor unit features an intelligent power saving chip, allowing it to operate for over six months on a full charge under normal usage. 4[User Friendly] The doorbell is designed with intercom light and battery indicator light, easy to monitor the status of communication and battery. 5[Waterproof Design] The doorbell is waterproof designed, can be easily and safely installed outdoors, ensuring durability.