Radio & speaker housing.  The REI 760871 comes with 2 5 inch REI speakers already installed, all you would need is to install a radio.  Made from rugged ABS plastic this housing makes it easy to have a complete sound system overhead.  Includes screw mounting hardware.  Mounting is thru the wide edge flange. 21 3/4" x 2 3/4" x 9" (WxHxD)