The present invention is a blend of a monovinylidene aromatic polymer, a rubber modified monovinylidene aromatic polymer, and a monovinyl aromatic-conjugated diene copolymer, which can be used to produce cost effective, transparent packaging materials with a good toughness, which materials can be produced using conventional thermoforming equipment. The blend comprises: a) from 49 to 70 weight percent based on the total weight of the blend, of a monovinylidene aromatic polymer having a weight average molecular weight (Mw) of from 210,000 to 400,000 and a melt flow of less than 12.0 g/10 min.; b) from 20 to 50 weight percent based on the total weight of the blend, of a rubber modified monovinylidene aromatic polymer comprising a monovinylidene aromatic polymer matrix having rubber particles dispersed therein, wherein the rubber particles comprise, based on the total weight of the rubber particles, from 25 to 100 weight percent rubber particles having a capsule morphology and a volume average particle size of from 0.1 to 0.4 microns; and from 75 to 0 weight percent rubber particles having an entanglement morphology having a volume average particle size of from 0.25 to 1 micron; and c) from 1 to 10 weight percent based on the total weight of the blend, of a monovinyl aromatic-conjugated diene copolymer, wherein: (i) the rubber and rubbery component in the rubber modified monovinylidene aromatic polymer and the monovinyl aromatic-conjugated diene copolymer range from 3 to 10 weight percent based on the total weight of the blend A; and (ii) the amount of the monovinyl aromatic-conjugated diene copolymer is less than 7 weight percent, based on the total weight of the blend A.