These are aluminum CNC cut S130 Side Splitters for your 280ZX and are sold as a set (driver & passenger). Mounting hardware is included.
Available in the Subtle profile in either raw aluminum or black powder coat.
Holes will need to be drilled into the car matching the corresponding holes in the splitters to complete the installation. See the video below for installation of Subtle profile side splitters (video is of S30 chassis installation, but it will be similar).
NOTE: provided rivnuts are size M5.