... 7inch TFT touch screen available,video calling &conversation with indoor extentions, guard centers, and outdoor stations,gate moniteringhandsfree function ... to 2; 2 to 1 & 2 to2; Dimension: ~ Indoor extention:230(L)x173(W)x30(H)mm ZAD522 Functions ... touch, Video calling, talking conversation & intercom w/ inside extension door phones, guard centers, Door releasing, monitoring according to signals ...