The Williams AV DLR 400 RCH is part of the Digi-Wave 400 line, a 2.4 GHz digital spread-spectrum (DSS) wireless platform built for secure two-way audio over frequency-hopping channels that resist interference. Digi-Wave transceivers and receivers support PIN-protected 87-bit or 87+128-bit encryption, OLED displays, and a working range up to roughly 900 feet depending on environment. This version uses the rechargeable lithium-polymer battery pack, giving extended run time without disposable batteries. It's commonly used for tour guiding, simultaneous interpretation, intercom communication, and government or corporate sidebar conversations where a secure, portable wireless link is needed.