With these kits, it's easy to add file storage to any drawer large enough to hold letter- or legal-size hanging folders. Two support rails mount to the inside faces of the front and back drawer panels, providing a sturdy base for attaching the side rails. The 25" side rails are made of thin steel sheet formed into a U-shaped profile for strength, and can be easily cut to length for a custom fit. Press-fit onto the ends of the side rails, hook-shaped caps snap onto the support rails, forming a rigid frame.