This read-write enumeration (eight-K, sixteen-K, thirty-two-K, sixty-four-K, marked DURABLE) sets the size of the switch's MAC address table in 1024-entry increments, though the description notes the 5226 and 5226A only allow the 8K setting. An admin would otherwise use this to trade off address-table capacity against the risk that a smaller table increases flooding of unknown-unicast traffic as a broadcast, but on this hardware the choice is effectively fixed at 8K. For example, an admin migrating configuration from a larger switch model that supports 64K tables would need to remember this specific 5226/5226A can only be set to eight-K(1).