One button remote UNLOCK is convenient and fast: The outdoor unit calls the indoor intercom, just answers the call to know the situation outside the door and confirm the safety. Press the unlock key to unlock the door immediately. Two-cor wire connection distance of 1000 meters, transmission clear more convenient and fast is clear, Outdoor call, indoor answer, voice transmission clear and loud, stable call quality. Side function button function is powerful Colour:White Material:Plastic Package Contents: 1x Telephone Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.