1. How to restore the normal size of sound-absorbing foam: 1. After opening the vacuum package, place the sound-absorbing foam in a ventilated place for 12-24 hours 2. Or soak the foam in water for 1 minute, wring it out, and let it air dry or use a hair dryer. 2. The principle of sound insulation foam is that the sound inside the sponge is repeatedly reflected back and forth, achieving the effect of noise reduction and sound absorption. These acoustic panels not only have effective sound-absorbing properties but also cause no harm to the body. The high-quality material of the studio foam can permanently maintain sound insulation properties. For cleaning, you only need to vacuum and dust occasionally. 3. High-density flame-retardant material: The sound-absorbing foam panels are made of flame-retardant and environmentally friendly materials, which can be used safely. The absorption spectrum is wide and over 500 Hz. High-density material, which is higher than the industry standard of 30 percent . At the same time, it can also improve sound quality: by absorbing harmful sounds, reducing fluctuations, reverberation, and vibration, useful sounds become clearer. 4. Installation: It is recommended that you attach tape to the four corners and the middle of the back of the sound-absorbing foam panels and then to the wall. Or you can buy spray adhesive to install the sound insulation foam according to your needs. 5. For professional acoustic control. Each sound-absorbing foam is delivered uncompressed and in good condition. With professional acoustic control, sound damping, acoustic processing, noise reduction, sound-absorbing foam is designed to reduce waves, reverberation, and flutter in small and medium-sized rooms. Acoustic panels are suitable for sound recording studios, rooms, home theaters, KTV, and all types of public places. Color: Black and gray Material: Polyurethane Size: 30 x 30 x 2.5 cm Package Contents: 12 x Black sound insulation foam 12 x Gray sound insulation foam Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture to be slightly different from the real thing. The allowable measurement error is 1-3 cm.