This queen box spring is built around a reinforced steel frame rated at 3500 lbs, so it holds a queen mattress flat and resists bending and sagging over the years. Standing just 4 inches tall, the low profile design pairs well with thicker mattresses while keeping the overall bed height comfortable to sit on and climb out of, and it works on a bed frame or directly on the floor. A shrink-resistant, removable fabric cover keeps the mattress from sliding and washes clean to maintain a fresh sleeping environment, while smooth rounded corner guards protect against bumps and scratches when you carry it through hallways and tight bedroom spaces. Please note that this listing is for the queen box spring only. A mattress is not included. Everything needed arrives in one package with clear instructions, so the foundation assembles in minutes.