Oil filter cover for Viper 125-200 cc motorcycles and similar (China, Minsk). The cover closes the oil filter (strainer) and keeps the oil in the engine lubrication system.
Replace it if there are cracks, a stripped thread and oil seeping out. Tighten the cover carefully: the part is aluminum, and overtightening breaks the thread. Install the part on a clean surface and observe the tightening torque of the fasteners.
