The QuietWalk QW50B1LT felt vapor barrier underlayment covers 50 square feet and measures 3 feet wide by 16.67 feet long at 3mm thickness. This premium underlayment provides sound absorption, thermal insulation, and moisture protection — making it ideal under laminate or engineered hardwood flooring. Still in its original box with no signs of use. QuietWalk is a leading underlayment brand trusted by flooring professionals for its density and performance on various subfloor types.