03 EC300 pro x piston rings- no marks - which way up?

[Johno74]

Hi everyone, i'd appreciate some help please:
03 EC300 used but still in spec, pro x piston rings - they don't have any marks to indicate which way up they should go but they DO have a slight lip [not as much as an L ring tho]

There's two rings and they both appear to be identical with the slight lip on one side so i'm guessing they need to be the correct way up(?)

The piston looks nearly new so i'm keen to reuse it and the rings for now.

I cannot find any information other than if they are marked put the rings on the piston with the marks facing up- no help in this case as there aren't any marks!

Can anyone help please?

[Skippa]

It seems amateur mechanics got out the forum

IMHO if no marks are present, it means there's no a specific way up as the ring shape should be simmetric.
If the shape is not simmetric, way up should be indicated with a letter printed.
More in general, i think that today any item industrially manufactured that requires a specific assembly way is designed and done with error proofing. If no error proofing, no way to mistake...