The Nebraska Blades Dust Cover is designed to keep the dust mess made with sharpening down. It comes equipped with a vacuum port to cut down on dust even further. This dust cover fits all CS-101 and CS-201 model year 2017 and newer.
If your machine is older than that, it will need the Dome (linked below). If you aren't certain what the model year of your machine is, this difference will tell you for sure: if the sides of the machine are shorter than the wheel, it is the older style-if the sides are taller than the wheel, it is the current style.