Steel Interior Frame With Steel Slats and a Poly Jacquard Cover HASSLE & HEADACHE FREE - The Quick Lock Metal Smart Box Spring comes together with easy-to-follow instructions, fewer bolts and absolutely no headaches; assembly that’s intuitive and packaging that seems to defy the laws of physics - now that’s what we call a new-age box spring DURABLY ENGINEERED - A durable steel frame is used to construct the interior framework of this foundation; twin size supports a maximum weight capacity of 350 lbs, while all other sizes can support up to 700 lbs LOW PROFILE DESIGN - A 4 inch height is perfect for taller mattresses or for those who enjoy their bed lower to the floor THOUGHTFULLY PACKAGED - All parts, tools and instructions are packed into one compact box that ships straight to your door; Quick Snap assembly system makes set-up intuitive and stress-free Worry-free 5 year limited warranty included; box spring only, a bed frame or platform bed is required to support this foundation and is sold separately