MB Base Sheet is a high-performance roofing base sheet, which is asphalt impregnated and coated with a glass fiber mat reinforcement. It has been designed to provide superior durability and ease of installation in asphalt roofing systems. By using only pure roofing grade asphalt, with little or no fillers, MB Base Sheet offers better flexibility and workability than typical heavily filled base sheets. MB Base Sheet may be used as a base ply in SBS, APP Modified Bitumen and Built-Up Roofing Systems.