The Digi-Wavetrade; system is a digital spread-spectrum (DSS), simultaneous two-way wireless listening system. Using it's frequency-hopping algorithm, it avoids interference and is a very secure method of communication. The Digi-Wave communication system allows users to listen and talk to one another wirelessly in a variety of scenarios.A Digi-Wave system consists of at least one transceiver (DLT 400) and various combinations of transceivers and receivers (DLR 400 RCH or DLR 400 ALK). Combinations of one or more DLT's and DLR's can be used to facilitate different events, depending on what needs to be spoken and what needs to be heard. Typical scenarios include: Guided Tours - with one or more tour guides (2-way), with audience participation (2-way), or without audience participation (1-way).Language Interpretation - one or more interpreted languages transmitted to audience (1-way).Intercom - with up to six people able to speak simultaneously, and even more listening.Hearing Assistance - featuring boosted audio for improved comprehension. The DLR 400 RCH is recharagble. If alkaline batteries are preferred, see the DLR 400 ALK.System includes: /gt;The DLR 400 has an internal rechargeable battery.