I do not own one, and have not actually handled one, but, there are pictures in all three of the Krag books (Mallory, Brophy, and Poyer). Basically it is a small, roughly cubical block of steel, fastened, with one screw, to the receiver just in front of the bolt handle, and above the rear end of the gate. I do not know if gate is modified (I do not think it is). There is a "T"-shaped opening on the top face of the "cube" into which the loaded clip is inserted - after opening the gate. Pushing down on the top cartridge forces them all (5) into the magazine with one push. The device functions exactly as you would expect it to, and the clip is unremarkable in appearance. According to reports, it actually worked fairly well, and probably would have been adopted if the Army had stuck with the Krag. However, the 1903 was well along, and clip loading was already an integral feature of that design.