... voice and video 4good stability over 300m door chime2.4 G Digital Wireless Video Door Phone Function Feature1) Transmission distance: 300m (free ... ).Visiting key wake up call, standby power-saving sleep5).Unlock door and alarm function .6).CE, ROHS , FCC available .7).83 ... approvedAccessory screw, rechargeable battery, ,manual, power adapter More than 300m door chime