Add an extra normally‑open (NO) signaling point to a compatible MARS contactor when you need more than simple on/off power switching. This auxiliary switch is commonly used to provide proof of operation (e.g., letting a controller know the contactor has pulled in), trigger status lights, or feed building automation inputs without tying into the power circuit. It’s a clean way to separate control/monitoring from load wiring - especially helpful during retrofits when you’re adding alarms, lockouts, or external interlocks but don’t want to redesign the panel. This is part of the A2L‑compliant auxiliary switch lineup intended for use with compatible contactors, supporting modern HVAC/R applications where A2L considerations apply. If you’re replacing older auxiliary part numbers as systems transition, this item is positioned as the updated A2L option for a 1‑NO auxiliary.