The Quik-Felt Synthetic Underlayment is designed to enhance the life of roof and is ideally suited for composite roof shingles and under metal roof applications. It is safe, 100% water resistant, wrinkle-free surface and offers resistance to JV breakdown and delivers better weather barrier performance compared to traditional 15 Lbs. & 30 Lbs. asphalt Felt products. The top layer is of PP Spunbond Non Woven Fabric with the scrim consisting of a hot extrusion melt of polyolifinic material while the bottom is specially designed to reduce slippage between the underlayment and the roof sheathing.