The Model 1871 Mauser was adopted as the newly united Germany’s first standard rifle, and it was a good design. However, it was a single shot rifle and soon it became apparent that the additional firepower of a magazine rifle was necessary to maintain military parity. A number of different conversion methods were tested by the German military , and ultimately a tube magazine under the barrel was adopted as the Gewehr 71/84.
One of the other competing designs was this external wraparound magazine. It held cartridges outside the rifle, with a mechanism to kick a cartridge into the action’s feedway when an empty case was ejected. While mechanically clever and probably reasonably reliable in sterile conditions, it has clear and serious disadvantages compared to a fully integral magazine like the type ultimately adopted.
The rifle was pulled from the auction after I finished my video, so it is not actually for sale. Doesn’t make it any less interesting to look at, though!