Chamberlain Ndis Wireless Doorbell & Intercom SystemBrand: ChamberlainIELNDISConvenient, Expandable Communication Inside Or Outside A Home1,000-Ft Range With No Wires Or Power ConnectionClear, Secure 900 MHz Digital CommunicationFully Secure ConnectionEasy To Use-Installs In MinutesExpandable With Up To 12 Units Per Network2-Year Battery Life-Requires 4 AA Batteries Per UnitIncludes 2 Weather-Resistant Wireless Portable Intercoms1-Year WarrantyProduct Class: Obs Systems/Home SecurityUPC: 834