Our Tote Express offers maximum storage capabilities with the ease of wheeled transport! The top unit is sized to hold albums and storage boxes, including ArtBin Super Satchel boxes. The reinforced front base adds even more support for safe transport of supplies. The bottom unit is securely mounted to the double, roller skate wheelbase and the locking, 2-stage handle. The top unit securely attaches to the bottom unit via sturdy buckles and a back strap that fits over the handle base. A shoulder strap on the top unit also allows this piece to be transported separate from the base. Top Unit is shipped inside Bottom Unit, some assembly required.