Special Features: 1. 4" B/W CRT 2. Handfree, video intercom 3. Waterproof and prevent dust design 4. 2-wire non-polarity system 5. Unlock monitor 6. With hand-move alarm threaten function 7. Camera adjusted angle Specification: 1. Power course: DC16V 2. Wait consume / operation consume: 1W / 10W 3. Screen: 4 Flat CRT 4. Effective resolution: 420 lines 5. Ring way: Ding dong ring or Chord are optional 6. External dimension: Monitor: 225L*170W*52H(mm) Camera: 127L*95W*35H(mm)