Sound Control & Crack Suppression Membrane for Ceramic and Natural Stone Tile Whisper Mat CS is a peel & stick sheet membrane that reduces impact and airborne sound transmissions, and isolates “finished” flooring from subfloor cracks. Designed for use with ceramic and natural stone tile where sound absorption is required, specified or desired. Constructed of a Cross Linked Poly-Olefin foam sheet combined with aggressive rubberized adhesive and a polyester mesh fabric, Whisper Mat CS also has the flexibility and strength to withstand structural movement and concrete shrinkage cracks up to 3/8″ without transferring stress load to finished tile. Additionally, excellent moisture resistant properties make this the most comprehensive underlayment product for ceramic and natural stone available.