The WMM450 is a fire-proof speaker back box for in-wall and in-ceiling installations in hollow structures. It is constructed out of power coated steel and allows installation for all kinds of flush mount speakers with a built-in depth up to ~ 115 mm. It provides an ideal environment for the installed speakers while preventing undesirable sound leaks into neighboring rooms. The dimensions of 446 x 455 x 127 mm allow it being placed in between a wide variation of wall studs or ceiling beams. It features an internal volume of 15 liters and comes pre-fitted with acoustic damping material for optimal acoustic performance.