This Rev-a-Shelf 432-WF39-3C 3 x 39 Inch Pullout Between Cabinet Wall Filler Shelf Organizer revolutionized otherwise wasted space in your kitchen. Normally a "filler" or extra space is simply covered up with a decorative front, but Rev-a-Shelf's line of fillers turns that otherwise wasted space into useful space. Fillers are intended to be installed in new kitchen cabinet construction and will not work in existing cabinets. This model is a 3'' wide design and features adjustable shelves with chrome rails and full-extension ball-bearing slides. Double check your cabinet's opening (inside dimensions) to allow the best fit. Measure side to side (width), front to back (depth or length), and top to bottom (height). Double check to make sure your product is within measurements and don't forget to take into account any obstructions (plumbing, hinges, etc.).