New UpgradedThis intercom system is the new upgraded version which uses new technology. It's a true full duplex system, hands-free use and easy to use. It also has better voice quality, longer signal range (1 mile), and lower power consumption. Comes with a detailed manual, written by a US client to help you use this intercom system better. [Thoughtful Design]: Wuloo specializes in designing and manufacturing FM wireless products for more than 20 years, with a philosophy of "customer first" incorporated in every detail. We have even designed wall mounts in the back of intercom units so you can install your intercom on the wall. The intercom can also work outside with the proper power bank (the power bank is not included). [Wuloo Brand] Wuloo are specialized in FM / ASK /FSK wireless techology for more than 20 years. Package equiped with quick start guide and detailed manual. [Expandable & Anti-Interference]: The intercom system is expandable: you can add up to 10 intercom units to a single system, perfect for home or business use. This intercom also uses new technology which gives it a strong anti-interference ability. Don't worry about receiving random conversations! [Fine Workmanship & Powerful]: Upgraded intercom system has fine workmanship and is more powerful. The MONITOR Function now has no time limit, an improvement from the last version. There are also 10 types of chimes available, the volume of the chime is adjustable, and the call volume can also be adjusted.