The CURT roof rack cargo carrier is a roomy and versatile cargo carrier with a lightweight design and easy installation. It features a simple 2-piece assembly and mounts to most styles of roof rack crossbars. With its strong steel construction and durable E-coat and black powder coat finish, it easily stands up to the tough trails and long miles ahead. This roof rack cargo carrier extension piece is designed to increase the storage area of the CURT roof rack cargo carrier #18115. With this extension piece installed, the cargo rack goes from a little over 10 sq. ft. of storage room to an impressive 16 sq. ft, providing a lot of extra room for storing bulkier items.