1. HANDS FREE DESIGN 2. DUAL TALING BETWEEN OUTDOOR STATION ANDINDOORMONITOR 3. BASIC FUNCTION: MONITOR, UNLOCK, TALK 4. ADJUSTABLE BRIHGTNESS, CONTRAST / CHROMA,VOLUME 5. EIGHT CHORD TUNES FOR OPTION IN INDOOR MONITOR 6. EXTENTION: 1 OUTDOOR STATION COULD CONNECT WITH 4 INDOOR MONITORS, WITH INTERCOMMUNICATION BETWEEN EACH OTHER