Sturdy all-metal construction consisting of two heavy-duty 1.5" X 3/4" rectangular steel tube outer frame. Internal mattress supports consists of 5/8" round tubes fully welded to the outer frame and center 3/4" square rails. Frames are assembled together with heavy-duty "U" clamps and quarter-twenty bolts. A tough powder coated paint finish is applied for long-lasting appearance and protection. Unit easily rolls on castors."