Use in conjunction with Adventure Bike Rear Racks (sold separately). Increases overall rack surface area for a variety of basic plastic storage cases or larger soft luggage bags to be securely installed. Easily attaches to rear rack with pre-drilled holes and locking tabs in several locations to mount more forward or back on the rear rack surface. Attaches by locking in the tabs to rear rack and tightens down with a hand knob included in kit. All mounting hardware and installation instructions included along with a threaded hand knob to install any variety of hard cases with center thread inserts. Detailed Specifications: Length: 15" / 38 cm. Width: 12-1/2" / 32 cm.