Abstract: This invention relates to a mass polymerized rubber-modified monovinylidene aromatic copolymer composition compositions with an improved balance of aesthetic, physical and mechanical properties, in particular, a combination of low gloss and good impact resistance in (co)extruded sheet and thermoformed/vacuum formed articles therefrom. A method for preparing such compositions and articles is disclosed. The improved gloss performance is achieved by maintaining the following relationship between the average rubber particle size (RPS) and the weight average molecular weight (Mw) of the matrix polymer: Mw?155?10?6*RPS6.