The T450P Sill-Pan System is designed with integrated Perimeter Drainage and Sill-Pan for Large Assemblies in Block-Frame Construction. The T450P is used for extreme weather-exposure with long runs of field-mulled window walls. For many applications the perimeter channel and sill-pan can be installed before Window Systems are delivered. All operable units associated with the T450N system are available in the T450P Sill-Pan System.