Vertiv Liebert SN-2D Two-Door Switch Monitor Sensor with Contact InputsVertiv Liebert SN 2D Two Door Switch Monitor Sensor with Contact Inputs The Vertiv Liebert SN 2D is a modular door switch monitor sensor designed for rack security and environmental monitoring in data centres, server rooms, and network closets. Featuring two dry contact inputs and modular connectivity with two connection points, the SN 2D allows for flexible custom string designs and daisy chain configurations to monitor multiple doors or access