ASU-15 Hardwood Flooring Underlayment is a semi-permeable moisture vapor retarder for use under hardwood flooring. This 15 pound Felt Underlayment consists of 30 lbs per ram of high melt point asphalt laminated between 2 sheets of Bs 30 kraft paper.Size: 36 inches wide x 167 linear feet longCoverage: 432 Square Feet per Roll