This is an APC Rack PDU 9000 series switched power distribution unit, built in a ZeroU (mounts vertically along the rack's rear, using no rack unit space) form factor. It's rated for 30A at 200/208V and provides 21x C13 and 3x C19 outlets — enough to power a substantial number of servers, switches and other rack devices from a single managed distribution point. Being "switched" means each outlet can be individually turned on/off and monitored remotely, which is useful for remote power-cycling a hung server or sequencing startup after an outage without a technician physically at the rack. The ZeroU design is specifically chosen for racks where every U of front rack space is needed for compute/network gear rather than power distribution.