Mattresses Foundations Standard Foundation Solstice Sleep A High Quality 9 inch Foundation for your mattress. AKA box spring Finish Color Charcoal Gray Profile Height 9 Foundation Twin AFDAY46-5010 TWIN $89.00 Foundation TwinXL AFDAY46-5020 TWIN XL $95.00 Foundation Full AFDAY46-5030 FULL $100.00 Foundation Queen AFDAY46-5050 QUEEN $119.00 Foundation King AFDAY46-5020X2 KING PAIR $190.00 Foundation Cali King AFDAY46-5070X2 CALI KING PAIR $215.00