This Springfield Armory manufactured sideplate is for the American model 1896 / 1898 Krag Jorgenson bolt action rifle and is in very good condition exhibiting a brownish gray patina with light wear and possibly some rust staining.  (file photo)

Note: Springfield Krag Jorgenson bolt action firearms with the following models and serial numbers have been observed with this part:

1896: 100706

1898: 118626, 253795 & 321871