This small accessory is used to clean the classic 23.9 mm diameter wheels, mounted on the Creality printers.
The procedure is straightforward: place the object on the rail, move the carriage towards the cleaner and drive it applying a little pressure. 8 cm of movement should be enough, not more.
It can be used in both directions, even if the flat part of the wheel is not likely to get dirty.
The long version is for those wheels that are difficult to reach, such as those underlying the plate of Ender 3.