Model Number:Yunxwdf16wpgn7t3 Item Weight:150 g Description:This is a portable doorbell system for home, factory, hotel, market, and more. Built-in microphone and speaker allow super sound quality for dual way communication. Simple and small design, easy to use. Specifications:Indoor Machine Voltage Range:5V USB Direct Power Supply Input Interface: Micro USBWireless Frequency: 467.6375MHzTransmission Distance: 200mWorking Time: 4 monthsWorking Temperature: -20 ~ 55 Size: Approx. 100 * 60 * 16mm / 3.9 * 2.4 * 0.6inApprox. 100 * 60 * 16mm / 3.9 * 2.4 * 0.6inPackage Size: Approx. 170 * 120 * 25mm / 6.7 * 4.7 * 1.0inPackage Weight: 150g Package List:1 * Indoor Bell1 * Outdoor Bell2 * Glue 1 * Screw Driver1 * User Manual Stable Transmission: 2.4GHz signal ensures stable and smooth transmission. The effective transmission distance can be up to 200 meters. Dual Way Intercom: When someone press the call button on outdoor unit, the indoor bell will ring immediately for reminding you. You can press the response button to talk with the people outside. Clear Sound: Built in high sensitivity microphone and speaker, allow audio input and output, ensure clear and smooth sound effect in communication. Adjustable Volume: The loudspeaker has big sound, adjustable volume size, and change the ring tone. The intercom has clear sound quality and can be used by mobile intercom Simple and Elegant: Ultra mini size ensure perfect portability and easy installation, small and nice, easy to install. Stable Transmission Dual Way Intercom Clear Sound Adjustable Volume Simple and Elegant