An SPDT auxiliary gives you a common point that can switch between NO and NC behavior - perfect when you want flexible control logic from a single signal. This version is identified as the right-side SPDT option in the MARS A2L auxiliary lineup, which matters when you’re fitting it into an existing contactor/assembly layout and need the correct mounting orientation. In real-world HVAC/R applications, SPDT auxiliaries are used for changeover signaling, enabling one circuit while disabling another, or providing a clean status output to controllers that expect a specific change-of-state. It’s also useful for retrofits where you’re uncertain whether you need NO or NC until commissioning - SPDT provides both options. This is part of the updated A2L‑compliant auxiliary switch range associated with compatible contactors, and is referenced as the A2L successor for the legacy SPDT auxiliary position.