Running in rings
Minute piston rings are also called run-in rings. Due to the geometry on the tread or the application of a running-in medium, these rings can better adjust to the cylinder surface.
Due to the geometry, these rings are marked TOP, indicating that they must be mounted to the pressure side. The initial surface of the piston ring that touches the cylinder wall during installation is small. The pressure between the ring and the cylinder wall will provide a counter-pressure to the pressure behind the ring. The ring can run in slowly and ensure that the other piston rings can do the same.