... sensitivity: less than -100.Product Name: Wireless Voice/Non-visual Doorbell 1,2.4G ISM Public Frequency Band:2402MHz-2479MHz2,Transfer ... distance: 500 meters for barrier free Details:Wireless intercom doorbell is a set of multi-way intercom system,can be ... not ring, the loud sound 'ding-dong', Outdoor monitorweight 15 beeps, re-timed one minute. wireless voice doorbell with clear voice for ...