How to restore the normal size of acoustic foam: 1. After opening the vacuum packaging, place the acoustic foam in a ventilated place for 12-24 hours; 2. Or soak the foam in water for 1 minute, wring it out, and air dry or use a hairdryer. High-Quality Materials: Our sound-absorbing foam panels are made of flame-retardant and environmentally friendly material, it is safe to use in small and medium-sized rooms. High-quality panels for better sound absorption, reducing waves, reverberation, and flutter echo in small to medium-sized rooms. The principle of the soundproofing foam is that the sound inside the sponge is repeatedly reflected back and forth, achieving the effect of noise reduction and sound absorption. The acoustic panels not only have effective sound absorption properties but also will not cause any harm to our body. The high-quality studio foam can retain its soundproofing function permanently. As for cleaning, you just need to vacuum and dust them occasionally. Installation: It is recommended to attach the tape to the four corners and the center of the back of the acoustic foam panels and then to the wall. Or you can buy adhesive to install the soundproofing foam according to your needs. Wide Use: The sound-insulating foam squares are an inexpensive solution for getting better recordings or in the studio. Used for professional studios, rehearsal rooms, concerts, podcasting, churches, home theaters, singing booths, home studios, offices, mancaves, dog kennels, storage rooms, and more. Size: 30 x 30 x 2.5 cm Material: Polyurethane Color: Black+Gray Package Contents: 6 x Black Soundproofing Foam 6 x Gray Soundproofing Foam Only the above package content, other products are not included. Note: Light and different screens may cause the color of the item in the picture to be slightly different from the real thing. The allowed measurement error is +/- 1-3 cm.