So called “bass traps” are used for acoustical treatment of different premises, ignoring the negative influence of the standing waves in the lowest frequencies of the sound spectrum. This usually is heard as a lack of bass. Our bass traps can be adjusted by raising and lowering the inner part to the disappearance of the harmful effect and accordingly the normalization of the sound picture in the room. Adjusting this inner part, we are increasing/decreasing the inner volume of the bass trap. Sо, we can use them to adsorb frequencies between 40 and 100Hz. This fact makes them widely usable without the need for special measurements and sound testing of the room. Everyone who buys such a bass trap can set it alone, according to his desire and his personal preferences. The traps are putted usually in the corners of the room, where you hear the most powerful „rumbling bass“, but anyone can experiment alone to achieve the desired effect. The traps need no mounting, they are free-standing on the floor. The outer diameter of the device is 39 cm, the height ranges from 55 to 90 cm, depending on how much is pulled inner part. Usually one small room ( to 10-14sq/m ) you will need one ( maximum two ) bass traps.