15" x 21" cart folds and unfolds in a single, quick, and easy motion. Cart ships fully assembled, no tools required. Collapses to 9" width and 10-1/2" width, respectively; stores easily behind doors, in between counters, or in the back of your delivery van for off-site functions. Durable construction; 3/4" solid aluminum legs and lock-tight bolts. Transports heavy loads and holds up to 350 lbs (approximately 116 lbs per shelf). sturdy polyethylene shelves have molded-in solid aluminum rods top shelf has ergonomically shaped easy grip handles at both ends SBC1521 shelf measures 20-1/2ˆ (l) x 15ˆ (w); SBC2031 holds two bus boxes per shelf; shelf measures 31-1/2" (l) x 18-1/2" (w); with 11-1/2" shelf spacing use for room service, dessert trays ,or table service, perfect for crowded kitchens and hallways or off-site catering 4" heavy duty non-marking swivel casters with molded-in metal reinforcement plates are permanently staked to legs for long life