Closed, the B&K 3 in 1s are a reflective surface perfect for a bright, lively room sound, while still controling bass frequencies.

On the inside of these units is a soft, fabric covered, heavy rockwool insulation, that offers broadband absorbtion. Opening the units by varying amounts offers a wide degree of compromise between a reflective room sound or a less-reflective room.

Another use for these units is isolation from other instruments. The doors of the B&Ks can be opened partially to create tighter, more controlled sound. This is very useful when recording multiple instruments at once, such as a band, where isolation is important.