As far I can see, no seams on the body or on the top (I checked with two magnifiers).

No engravings on the button, which catches a little, but that's to be expected.

No blots or stains or anything on the side of the body, it has fine lines (brushed?) which can not be felt under the finger. On the top there are also those lines, concentric. It is pretty heavy, I'm almost sure it's pure SS.

Has an indent for the battery positive and a circlip on the button.

I haven't checked if other buttons of the older ones fit because I can't find them ATM. :(

The threads on the button look rather coarse, so maybe they are non-standard size.

But regardless, by itself, the mod is pretty good value and I can find no obvious problems with it in the few hours that I have it.