The monitor you see at the top of this sound rack is connected to the CALink program (reviewed here on this site) for the CA21 automations, which are located in the sound racks for ease of use. Dolby CP650s setup for EX are used in all auditoriums. The two silver items in the rack are an AV input switcher to select between the intermission preshow, satellite tv receiver, DVD player or an auxiliary input. The DVD player is the 2nd silver piece of equipment you see above the QSC monitor/crossover. The bottom two units are UPS battery backups for the Dolby processor, CA21 automation, QSC monitor/crossover and Kelmar dimmer control circuit.