My first EKII
I have been wanting to purchase one for several years, but other purchases kept getting in the way!
Here is my first WWII EKII, a salty one that came with an envelope. I bought it thinking it was unmarked, however I was pleased to discover that the ring is stamped "55" for J.E. Hammer & Sohne. I like worn and "been there" items, and while this pales in comparison to the mint and shiny examples out there, I am pleased!

The envelope is not maker-marked. Is this type correct for this maker?
The edges of the cross aren’t pretty and have some oxidation. I am the type that leaves things alone, but would anyone recommend any cleaning to better preserve it? All feedback and tips are most welcomed!
Thank you for any advice!
Johannes