The HS1T4ZZV is a 1 Water Delivery Temperature, 4 Zone by Zone Valves Zone Panel. This panel can be used with any of the four Zoning By Zone Valves Integrator Panels (HSPS120MZL, HSPS120MZH, HSPS190MZL, HSPS190MZH, as well as any of the Zoning By Zone Valve Boiler Pro Integrator Panels; HSBP4W-xxP-S-MZL, HSBP6W-HS115MZH or the HSPS150MZH-HTP Panel for use with Westinghouse boilers). This panel requires 4 thermostats, 1 for each zone.