Honeywell Q7300D2002, Microelectronic Commercial Heat Pump SubbaseCondition: * New, Old Stock. Never Put Into Service. In OEM Packaging. As Pictured.Additional Notes:* Use with T7300E, F Thermostats in a 24 Volt AC 3-stage heat and 2-stage cool heat pump system.* Power direct from 24 Volt AC transformer.* X1, X3, X4 terminals power to field configurable LED’s.* AS terminals for optional discharge air sensing.* A1, A2, A3 terminals for optional economizer.HoneywellQ7300D2002