Mattresses Foundations RB Econo Box Economy rebuilt foundation Foundation Twin RBECOBOX-T Twin $40.00 Foundation TwinXL RBECOBOX-TXL Twin XL $50.00 Foundation Full RBECOBOX-F Full $50.00 Foundation Queen RBECOBOX-Q Queen $60.00 Foundation King RBECOBOX-K King Twin XL Pair $100.00