Designed for use as a wireless doorbell and inter for residential as well as mercial applications1000 foot range with no wires or power connection requiredCrystal clear secure 900MHz digital municationAdvanced features include voice activation and monitor modeBroadcast to all channels simultaneously or speak to one party with Secured LinkSingle or multi-channel municationExpand up to 12 units per workRequires 4 AA batteries per unit (not included)1-year warrantyCompatible with wireless inter models NDIS NTD2 and NLS1