The Hercules Universal Heavy Duty Adjustable Metal Bed Frame with Double Center Support Bar and 7 Rug Rollers with Locking Wheels fit Queen, Twin, Twin XL, Full, Full XL, King and Cal King Size mattress sets. This solid black matte powder coated steel bed frame is engineered to support heavier mattress sets and feature adjustable sliding end rails. The extra-strength double rail center support bar adds extra support to your mattress and box spring in the middle to prevent sagging. Many manufacturers warranties require a center support frame. The center bar is extra wide at 2 ¼ Inch-for extra stability. 7 rug rollers make moving the mattress easy and all of the wheels lock into place to prevent further movement. The sturdy side rails keep your box spring in place so it cannot shift during use. Headboard Brackets attach to any headboard and screws that attach the bed frame to headboard are not included. Interlocking frame is easy to assemble in minutes and no additional tools are required. An additional extender bar is included for the King and California King sizes.