That's for a Marble's, not something that was offered by Lyman in the originals as far as I know. They also had them for Lyman's but sold out -
.buffaloarms/47-stem-lyman If you ever see one in a Marble's it's almost certainly a reproduction, or possibly an original with a Marble's stem put on it. I will be trying to post a thread about these in a day or two, been going through my catalogs and trying to find my examples.
Added - If a sight was shipped with this stem it was called the No 52, just a standard sight with this stem installed from what I can see. I have a No 52 with box for Savage 22's and holding it on a couple guns it will adjust low enough for some, but on a couple early Model 1903's it will not quite go low enough to line up with the lowest barrel sight setting. If the sight wasn't in a marked box, there would not be a way to say it wasn't just a regular sight that had the stem replaced.
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