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-Density Flame-Retardant Material: The sound absorbing foam panels is 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%. At the same time, it can also improve sound quality: by absorbing harmful sounds, reducing fluctuations, reverberation, and vibrating , Useful sounds are clearer. 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 glue to install the soundproofing foam according to your needs. For professional acoustic control Acoustic Foam Each comes uncompressed and in prime condition! With professional acoustic control, sound suppression, acoustic processing, noise reduction, the acoustic foam is to reduce the waves, reverb and flutter in small and medium-sized rooms.Acoustic panels is suitable for sound recording studio, listening. Colour: black+gray Material: polyurethane Size: 30 x 30 x 2.5cm kage Contents: 6 x black sound-absorbing cotton 6 x gray sound-absorbing cotton Note: with adhesive, the color of the adhesive is random, don't accept the specified color 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 a little different from the real thing. The measurement allowed error is +/- 1-3cm.