Nice find!
Although one of the most numerous of Krag carbine sights, the 1901 version is in demand and is bringing good money.
IMHO - It is probably more sought after than the far rarer model 1898 and 1902 carbine sights.
Another aspect of the model 1901 carbine sight, (and also the ultra rare BoO&F sight), is that both legs of the sight leaf are of obvious equal width.
The "channel" the 'eye-piece' travels in is straight, with all edges parallel to outside edges of the sight leaf.
On the rifle version, the 'channel' angles to the left as the slide is raised, to compensate for bullet-drift. This makes the legs of the leaf appear to differ in width.
(Lately, a lot of 1901 rifle sights get listed on eBay as "carbine" sights. Looking at the leaf for this built-in feature allows identification, even in poor photos).
![Image](https://kragcollectorsassociation.org/kca/phpBB3/images/yabbfiles/Attachments/1901_Carbine_Sight_001.jpg)
![Image](https://kragcollectorsassociation.org/kca/phpBB3/images/yabbfiles/Attachments/rifle-1901_leaf.jpg)