This read-only object reports the power guard band, in watts, that the system reserves and will not allocate to additional ports, in order to avoid overcommitting the PoE power supply. An admin uses this to understand why the switch stops enabling PoE on additional ports before the power supply's rated capacity is fully consumed on paper. For example, an admin surprised that a port fails to power up even though the rated PSE wattage appears to have headroom left would check this guard band value to understand the safety margin being reserved.