1U Rack UPS -- battery buffer for the whole chain wired to it. Same power-port shape as a PDU (an "in" to the grid, outlets downstream), but it stores charge instead of just passing load through.
1000W capacity, 4 outlets. Starts completely empty on install -- it only charges while its "in" port is wired into a live Residential Grid slot, so day one it offers zero real protection until it's had time to fill.
Exists for exactly one job: keep critical gear alive through a brownout. When a grid slot goes dark, anything drawing power through a bare PDU on that slot drops immediately -- anything behind a sufficiently-charged UPS on the same slot keeps running.
Like a PDU, it's exempt from ever being the device an intrusion fault lands on directly -- but a brownout doesn't care about that exemption, and an empty battery is exactly as useless as no UPS at all.
Its outlets aren't limited to its own rack either -- cross-rack cabling lets this UPS carry a device racked in a second, physically separate rack through the same brownout protection. A device fed that way is treated exactly like a locally-powered one everywhere it matters: thermal wear, overload/fire risk, disaster-recovery eligibility, and revenue tracking all apply identically, no partial or second-class powered state for a cross-rack link.
Tip: charge time matters -- wire it in and let it sit on a live grid slot well before you actually need the buffer. A UPS installed mid-brownout won't save you.
See also: the Game Systems manual's Fire & Smoke Hazards section, Utility Billing & Dynamic Pricing section, and Cross-Rack Power section.