This is the most flexible auxiliary in your list: two SPDT changeover contacts in one add‑on. That means you can manage two independent changeover signals whenever the contactor energizes - ideal for more complex HVAC/R control schemes, staged equipment, or applications where you need both status feedback and interlock changeover without adding extra relays. In practice, one SPDT might feed BAS (or a controller input), while the second handles a safety/permissive circuit or alternates control between two functions. It’s also valuable for retrofits because it can replace multiple single‑function auxiliaries and keep wiring cleaner. This auxiliary is explicitly part of the new A2L‑compliant auxiliary switch range (61598–61605), referenced as compatible with contactor families that accept these updated auxiliaries - helpful when you’re standardizing during the A2L transition and want one part that covers a lot of control logic needs.