Preassembled Rollout Shelf System for 33" Cabinet Openings. Featuring 21" Undermount Soft Closing Drawer Slides. Preassembled and ready to install mounts to bottom of cabinet. Soft closing undermount slides. 5/8" White Birch rollout drawer box with UV coating with1/2" bottoms. Overall Dimensions: 31 1/16" wide x 21 7/16" deep x 7" tall.