Professional Solution for the Studio Soundproof Why choose Donner First,we strictly follow the optimal ratio of raw materials to produce each piece of donner acoustic foam. But some sellers will replace one of main compositons with cheap stone powerder, which of couse can lower the cost so that they can sell them at low. Outwardly, it look the same, but in reality, that inferior acoustic foam CAN NOT pass the Test of Flame Retardancy conducted by SGS test report lab. Definitely, Donner acoustic foam have passed the SGS test. Second,we also have sent our acoustic foam to Building Environment Testing Center of Tsinghua University to test its NRC(Noise Reduction Coefficient). And the test results show the NRC is 0.8, which is a brilliant number because when NRC is greater than or equal to 0.8, its Noise Reduction level is A-class. ---Donner Acoustic Foam Panels Quality Kit In a recording studio, the hard wall surface will give us unnecessary sound reflections, and the corners of the room will give us unnecessary reverberations, causing the problem of unclear sound. Donneracoustic foam panels can solve such problems well.Donnersoundproofing foam uses a new polyurethane sound-absorbing material, which is processed and formed through a mature foaming process and can greatly improve the sound quality in your room. Notice the difference between sound absorption and sound insulation. Package Included: 12 x Donner Acoustic Foam PanelsUse Attention When you open the package and take out the product, you may find that its thickness is smaller than expected. Do not worry You can soak in water for 5-10 seconds and then blow dry to restore the normal thickness. NOTE: Stickers and acoustic foam spray adhesive are not included.--- How to Install --- Note before installation:You can choose to use stickers or acoustic foam spray adhesive to fix the foam panels. When use stickers, please make sure the wall is flat and free of foreign matter such as powder, which will affect the effect