A hybrid between mobile and stationary storage, these cabinets have interlocking grooves for easy and secure stacking. The housing is made from dent proof polypropylene. The IDS system truly gives you mastery over your storage space with fully expandable draws and removable cases. From 1 compartment to 100 compartments, each individual case fits into its own tray within the cabinet and can be easily and quickly removed to be taken to a remote site while keeping the parts secure. The box has 4 fixed compartments which run length wise in the box and measure 13-1/8" x 2-1/8". The box also comes with 16 IDS dividers which can be placed in various locations. Item 53986 is just a case; 53999 is the cabinet only (no cases).