Sound-absorbing effect is good, FR,Rohs,svhc Noise reduction GB,BS-5852 or TB117 color sound muffler sponge absorb a large number of incoming acoustic energy of the acoustic attenuation, reducing the interference and echo sound reflections ,improve the purity of the sound Dear friends, Hello, First of all ,thank you very much for your concern of our products, In order to provide you the accurate informaton of the product \' material and quotation fastly and timely . Please inform me of the following information when you make an enquiry . Many thanks! Providing samples to me is the best way . Size Demand Quantity Materials and density (weight per cubic meter) Drawings Material Details Usage and product color and packing requirements color sound muffler sponge