In box. USAN10–44597-QAB,4-8 This Upholstered Platform Bed is designed with a modern wingback headboard, smooth velvet, and a soft sponge that wraps the entire bed frame. No box spring is needed, and it still supports a box spring in case. With 47" / 51" adjustable headboard. The gap between slats to the headboard is 9.8” to 13.8”. Suitable mattress thickness: 8”-14”. The mattress is not included. This velvet bed frame is made from a sturdy, high-quality metal frame. The center support legs blend naturally into the sturdy frame, providing dense and powerful support. Weight capacity: 800 lbs. The 8" under-bed storage space is perfect for storing extra odds and ends. We added velcro straps under all slats to facilitate installation and prevent squeaking between the wood slats and metal frame, which makes this bed frame virtually silent. The assembly instructions are very clear and easy to follow and you can have your bed frame in under 1 hour.