This is the fine cartridge filter for Kokido's pool robots, reference RC32-09. It fits the RC25 and the RC32, the machines sold under the names Manga and Manga+. Each order supplies one cartridge.
The filter is a pleated white filter cloth in a grey plastic frame with a lip on either side. Fitting it takes no tools: lift the basket out of the robot, set the cartridge into the debris chamber and click everything back.
The fine version is specified at 80 micron and is meant for fine material such as sand. It is washable: the manufacturer advises rinsing it out after every use and replacing it once it shows wear or loses flow.
A filter is a wearing part, and how often it needs replacing depends on how dirty the water is and how often the robot runs. Worth having a spare in the house before the swimming season, so there is no waiting when the old one has to come out.