STEICO Natural acoustic wood fiber underlayment 3-ft x 2-ft x 6-mm Premium Cushion Flooring Underlayment (90-sq ft /Panel) in the Flooring Underlayment department at Lowes.com
QuietWalk 100 sq. ft. 3 ft. x 33.3 ft. x 3 mm Underlayment with Sound and Moisture Barrier for Laminate and Engineered Floors QW100B1LT - The Home Depot
Hardwood Floor Underlayment - California Flooring and Design
FloorLay 9 - High Performance Acoustic Underlay for Laminate, Wooden floors & Carpets
ProBase® Rubber Underlayment For Engineered Hardwood & Laminate Flooring - Sound Seal