Two Mosin-Nagant stripper clips.
A stripper clip is a clip that is simply one thin piece of metal that cartridges can clip into. Used largely to easily load bolt-action rifles in WWI / WWII, they saw multiple uses on the battlefield. The Kar 98k and the Mosin-Nagant are a couple of rifles that were issued with stripper clips. They are called "stripper" clips because the cartridges are stripped off the clip into the magazine.
Early machine guns such as the Perino Model 1908, Hotchkiss M1909/M1914 and the Japanese Type 92 heavy machine gun used another form of stripper feed.
The proper nomenclature for this item is a "Charger". The original ammunition "clip" was developed by Ferdinand Mannlicher for his M1885 rifle. It is of the "enbloc" design, where rounds and clip together are inserted into the weapon and, as the ammunition is used, the clip is ejected. Mauser liked the idea of faster reloading by using this design but did not like the idea of an open hole in the action.(Where the clip was ejected) So, the "charger" style of ammunition clip was delevoped.
The Soviet SKS rifle uses a 10 round charger for loading. Also, 5.56 NATO rounds are issued in 100-round bandoliers (in 10 chargers of 10 round apiece), along with a magazine adapter.
The Mauser M1896 "Broomhandle" pistol also uses a 10 round charger clip.