The Shure PA821A 8-Channel Antenna Combiner is a complementary accessory for Shure PSM Personal Monitor systems. When multiple systems are required for monitoring environments, the PA821A combiner quietly and efficiently optimizes RF management for up to 8 PSM transmitters when racked in a central location, while also reducing rack clutter. The PA821A Combiner is a replacement for the PA821SWB Antenna Combiner.