What makes our product different- Our slide-out shelving unit will include both drawers, pre-assembled to a framework. Eliminating any "mounting" to the sides of the cabinet. The framework simply slides into the opening with both drawers attached, the unit will then fasten down to the bottom of your cabinet with 4 screws. Our deluxe frame kit only takes minutes to assemble. The width measurement represents the full outside dimension including the framework. Your cabinet opening should be at least 1/8" larger than your selected size. When measuring the width, of a single door cabinet - but the inside of the door hinge, and measure over to the opposite side of the opening. You're trying to measure the narrowest part of the opening. On double-door cabinets, measure in between both door hinges. All of our drawers are handcrafted from 9-ply Baltic birch. Drawers and shelves come with a very durable UV-clear finish. We only use heavy-duty full extension guides and there is no extra charge, we want to bring value and quality to your home.