MBTechnology, Fresno, Calif., manufactures a full range of underlayments for tile, shingle and metal roofs. The addition of SBS rubber to asphalt gives layfastSBS an elastomeric property that is not available in common felt. The product also contains a higher percentage of asphalt for increased waterproofing protection. Its inorganic fiberglass reinforcement eliminates the rot and deterioration associated with saturated felt, allowing sharp bends up to 90 degrees without cracking or fracturing. This underlayment exceeds ASTM D226 standards.