InsulFoam FL (Flute-Fill) is a custom-made and high-performance insulation consisting of a superior closed-cell, lightweight expanded polystyrene (EPS). This InsulFoam FL offers a long-term, stable R-Value and has excellent dimensional stability, compressive strength and water resistant properties. It is cut from the same high quality stock as flat InsulFoam products and, upon request, will be manufactured to meet Standard Specification for Rigid, Cellular Polystyrene Thermal Insulation.