Shure PA821A Antenna Combiners are complementary accessories for Shure PSM Personal Monitor systems. When multiple systems are required for monitoring environments, the PA821A combiners quietly and efficiently optimize RF management for up to eight PSM transmitters when racked in a central location, while also reducing rack clutter. PA821A combiners ship with UA802 Coaxial Cable. PA821A combiners replace PA821SWB Antenna Combiners.