FloorComfort 4-ft W x 25-ft L x 5 T Premium Foam Moisture Resistant Flooring Underlayment (100-sq ft / (Fan fold) in the Flooring Underlayment department at Lowes.com
Rubber Underlayment - Rubber Flooring Direct
5mm or 6mm Gold Underlay - Wood or Laminate Flooring Acoustic & Heat Insulation | eBay
Floorlot GoldMax 200 sq. ft. 3.58 ft. x 56 ft. x 3 mm Premium Underlayment for Laminate Hardwood and Engineered Floors FL-019 - The Home Depot
AbsorbaSound 5 mm Acoustical Rubber Underlayment for Hard Surface Floors 100 sqft. Roll | LL Flooring
5mm Sonic Gold Flooring Underlay Available at Leader Trade