The Nailable Underlayment is a premium product that delivers exceptional long term weather barrier performance compared to traditional asphalt felt products and other synthetic underlayments. The Premium Underlayment is 100% synthetic with slip-resistant coatings on both sides. The textured top side contains a rubberized polyolefin coating that provides unsurpassed slip resistance ensuring a safer and more secure work surface. The bottom is designed to reduce slippage between the underlayment and the roof sheathing.