How To Recover The Normal Size Of The Acoustic Foam: 1. After opening the Vacuum package, place the Acoustic Foam in a ventilated place for 12-24 hours; 2. Or soak the foam in water for 1 minute, wring it dry, then air dry or use a blower dry. High quality Materials: Our sound absorbing foam panels crafted from fire-retardant and eco-Friendly material, it is safe to use in small and medium-sized rooms. High quality panels for better sound absorption, Reduce waves, reverb and flutter echoes in smaller to medium sized rooms. The principle of the soundproofing foam is that the sound inside the sponge is repeatedly reflected back and forth, thereby achieving the effect of noise reduction and sound absorption.the acoustic panels not only have effective sound absorption characteristics, but also will not cause any harm to our body.The high quality material studio foam can keep its sound insulation function permanently. In terms of cleaning, you just need to vacuum and dust them occasionally. Installation : It is recommended to stick 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 purchase spray glue to install the soundproofing foam according to your needs. Widely Use: The sound proofing foam squares are a low cost solution to get better recordings or in the studio. That used for professional studios, rehearsal rooms, concert , podcasting, churches, home theaters, vocal booths, home Colour: black + white Material: polyurethane Size: 30 x 30 x 2.5cm Package Contents: 6 x black sound-absorbing cotton 6 x white sound-absorbing cotton Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.