The Wonder Bin 3-Toolbox System is a stackable and expandable 3-pc.mobile toolbox system that allows you to customize how you transport your tools and accessories. Three separate storage boxes can be connected by easy clips, depending on your needs.Top box has 9 divider bins and measures 21.2in.W x 15.7in.D x 5.11in.H. Middle box has two adjustable dividers and measures 21.2in.W x 15.7in.D x 8.78in.H. Bottom box has two adjustable dividers, telescopic handle, built-in trolley with wheels for transport, and measures 21.2in.W x 15.7in.D x 27.17in.H. All have modular covers with aluminum latches. Made of sturdy polypropylene and polycarbonate.