CorStone Optimum Series is made from 5.0 Acrylic, their heaviest grade of acrylic. The Optimum Series includes the same great features of the Advantage 3.2 Series, like the non-porous acrylic that is impervious to staining. CorStone sinks can stand up to tomato sauce, red wine, even iodine, no unsightly scuff marks in the bottom of your sink from pots and pans. The Optimum 5.0 Series can absorb and disburse impact, making CorStone sinks more resistant to denting, chipping and cracking. The same absorption and disbursement property work to minimize running water and garbage disposal noise.