A COMPREHENSIVE SECURITY SOLUTION TO MAKE YOUR HOME SAFER WIRELESS INTEGRATION WITH YALE DIGITAL DOOR LOCKS: In sync with Yale Digital Door Locks for enhanced security 200 PICTURE MEMORY WITH DATE AND TIME STAMP: In-built memory to store up to 200 photographs of your visitors for greater reliability 4-WIRE SIMPLE CONNECTION: Hassle free connection with minimum wiring UP TO 4 INDOOR & OUTDOOR UNITS: Configuration can be expanded with as many as 4 monitors and 4 door cameras Call transfer between indoor monitors OUTDOOR UNIT FEATURES: Water & vandal-resistant Cast aluminium: Built to endure some of the toughest situations White LED lights for clear night vision