The 8PSBX is molded high density polypropylene plastic. This provides lightweight, economical and rust resistant performance. The natural acoustic properties of plastic combine with engineered ribs on the interior of the backbox to provide effective resonance and vibration control. It is furnished with factory installed 8-32 screw retaining clips for grille mounting and includes four pre-molded thin-wall knockouts which may be easily drilled to permit conduit entry. To facilitate mounting in suspended ceiling construction, Model 8PSBX may be used with Lowell tile bridge Models LBS8 or LBS8-R1. The standard factory color is black.