I noticed this 'no-drill' receiver sight listed today on e-bay. I have not seen one like it before. It appears possibly to be 'Home-made', but, skillfully done. The windage screw looks a lot like the rear sling-swivel cross-screw from a Norwegian Krag carbine. It also appears to use a re-shaped Krag magazine cut-off. The knob on the elevation lock-screw looks kind of like a 1903 Springfield, rear-sight elevation knob, to me. Obviously, made by someone with more time and skill than money (to buy a Pacific K-1 sight).