Polypress is a pressed flake foam, also called polypress. It is available in various density types. This product is used, among others, for decoupling floors (causing them to 'float'), in which case you purchase a finishing layer such as a double gypsum fiber board yourself (possibly in combination with OSB board).
You can read more information about the applications of the various types of Polypress on the Polypress Vibration isolation product page. An alternative to floating floors is the ready-to-use product Akoestifloor.