The fireplace insulation system that makes a difference. If you are building a false chimney breast for a cassette/inset type fire place then the Promafour provides the ideal solution. The Promafour System is a safe reliable, robust system developed to resist continuous high temperatures of up to 1000°C. The Promafour System is sold through our designated specialist stove and fireplace stockists. are also suitable for use use behind a wood burning stove or heating appliance.