Serta SleepTrue Standard Box Spring Twin XL Size Brand new Includes 5 Year Limited Warranty, The Serta SleepTrue Standard Box Spring features top quality foundation with excellent durability and long-lasting quality. Its design provides superior support for all mattresses and comes in various sizes. Every SleepTrue mattress model undergoes eight rigorous performance and durability tests to ensure your mattress is as comfortable and provides durability down to the last stitch. SleepTrue Standard Box Spring Boxspring Foundation, Top quality Foundation