The ProLink 500 Wireless Intercom Package (PRO-540) is for 4 users, and comes with a portable, digital, wireless intercom system. It allows full duplex communication between four users simultaneously, without the need for a base station. This package comes with one Master belt pack, three Remote belt packs, and four lightweight headsets and your choice of dual or single muff earpieces. ProLink 500 belt packs include three “AA” rechargeable NiMH batteries, and also comes with one gang charger, and a sturdy cardboard carrying case for easy transportation. This system has the ability to transmit up to 500 feet line of sight, and allows communication through walls and glass. There is also the option to add an unlimited number of listen-only belt packs to the system. Other features include A/B channel selection, "Push to Talk" or "Always On" modes, and LED indicators that alert you if you've gone out of range or are low on battery. This system is perfect to use for the theater, local television studio, in a church setting, or during training exercises.