Up to 2 doorbells can be connected with 4 indoor monitors(The slave monitor is MZ-VDP-739EM). Dual-Way Communication between indoor monitor and outdoor camera; Call Transfer among monitors.You don't always go downstairs open the door after install the multiple intercom. You can check the recording via smartphone anytime. 7 Inch LCD Monitor and video Doorbell? 7 inch TFT display monitor with slim design, touch-key operation, hand-free, Support Wifi/RJ45 port connect to internet(Only connect to 2.4GHZ router band). Outdoor doorbell with waterproof cover, built-in infrared sensor and 1080P camera, 115º wide view angle, Night vision, Rainproof, Dustproof, and Anti-vandal, It can connect all the electronic lock. As our valued customer, we will do our best to make sure the product you receive arrives to you on time and as expected. This item is in the category "Home & Garden\Home Improvement\Home Security\Door Entry Systems & Intercoms". The seller is "reefbenmeir12-5" and is located in this country: US. This item can be shipped to United States.