Frame and supports: 1″ square aluminum tubing with 0.063″ wall. Gussets: Each frame and cross support junction shall be joined with a two-piece die-stamped aluminum gusset, riveted to frame and cross supports. Tray slides: extruded aluminum sections with a 9/16″ lip and beaded edge, spaced 1 1/2″. Casters: 5″ diameter NSF-approved, non-marking rubber tired wheels on swivel stem plated casters with polymer tread. Shipped knocked down.