Leather holder for the sheath of German Mauser 98k bayonet. Made of black leather. Aluminum parts. Well assembled, durable, low price.
Frogs without the tab, that presses the handle of the bayonet, is the original model. The tab appeared a little later (1941 in the infantry, the year before in the cavalry).
The distribution of the model with the tab started, when it became clear that soldiers often lose their bayonets (the leather carrier kinked at its narrowest part, and the bayonet fell out under its own weight). Later the frogs with the tab become standart.