Provides superior protection against water, air and moisture infiltration in window and door openings, corner boards, under stucco finishes, masonry walls and other flashing areas. The product is 40 mil thick and is designed to meet the requirements for weather resistive barriers as defined by Federal Specification UU-B-790a, Grade A. It is designed to work in severe winter climates, milder climates, and in coastal areas where wind driven rain is common. It should not be used on roofs. Vycor® V40 is compatible with wood, plywood, oriented strand board, concrete and masonry and fully adheres to the substrate to prevent water from passing through and into the structure. Available in a range of widths: 6", 9", 12", and 18" to accommodate a variety of job requirements.