I do have a king size mattress BRAND NEW IN THE BOX FOR AN ADDITIONAL PRICE... Description The Next Generation Bed Frame - The SmartBase Mattress Foundation by Zinus. The SmartBase eliminates the need for a box spring as your memory foam, spring or latex mattress should be placed directly on the SmartBase.   Uniquely designed for optimum support and durability the strong steel mattress support has multiple points of contact with the floor for stability and prevents mattress sagging, increasing mattress life. The SmartBase bed frame is 14 inches high with 13 inches of clearance under the frame for valuable under-bed storage space. With plastic caps to protect your floors and an innovative folding design to allow for easy storage, the SmartBase is well designed for ease of use.