The HS2T3ZPMP is a 2 Water Delivery Temperature, 3 Zone by Pumps Zone Panel. This panel can be used with The HSPS120MPH, HSPS190MPH, HSPS150MPH-HTP, or the HSBP6W-HS115-MPH integrator panels. This panel is desinged to be used when you have two different emitter types that reqire two different water deliver temperatures. For example, tubing in concrete should never go above 130° while baseboard usually requires 145°-160°. If you had both of these emitters, you would need a 2 Temp Panel.