STANLEY FATMAX PROSTACK™ Shallow Box (No Foam insert included) (440 x 162 x 333mm) is an interlocking stackable storage system built for work and designed to work for you and offers real versatility - whatever the task. Packed full of user-friendly features STANLEY FATMAX PROSTACK™ is the perfect partner to help you get the job done quickly and professionally. Each and every PROSTACK™ unit features a strong interlocking catch system to let you connect and disconnect units quickly and easily.