Steel Interior Frame With Poly Jacquard TWIN XL DIMENSIONS - The dimensions of this XL twin size box spring are 78.7 x 38 x 9 inches. The length is 5 inches longer than our Standard Twin size. Please measure your bed frame to ensure compatibility EASIER THAN EVER ASSEMBLY - As if its ultra-durable steel structure and convenient packaging weren’t impressive enough, this box spring features tool-free locking brackets for intuitive setup, assembly takes only minutes to complete DURABLY ENGINEERED - Durable steel is used to construct the inside framework of this foundation; Twin/Twin XL sizes support a maximum weight capacity of 350 lbs, while Full, Queen & King sizes can support up to 700 lbs VERSATILE FIT - Compatible with all Zinus mattresses and bed frames; please confirm dimensions before using with non-Zinus products WARRANTY INCLUDED - Included a 5-year limited warranty for the box spring only; a bed frame is required to support this foundation and is sold separately