WIRELESS INDOOR/OUTDOORPROTABLE INTERCOM Designed for use as a wireless doorbell and intercom for residential, as well as commercial applications1,000 foot range with no wires or power connection requiredCrystal clear, secure 900MHz digital communicationAdvanced features include voice activation and monitor modeBroadcast to all channels simultaneously or speak to one party with Secured LinkSingle or multi-channel communicationExpand up to 12 units per networkRequires 4 AA batteries per unit (not included)1-year warrantyCompatible with wireless intercom models NDIS, NTD2, and NLS1