This Magnum magazine box is an original Winchester part, for use with what Winchester used to call the "short magnum cartridge" rifles (.264 Win Mag, .300 win Mag, .338 Win Mag, etc. - not to be confused with today's "WSM" and "WSSM" cartridges). These boxes are used in excellent condition.
We use the NRA Modern Gun Condition Standards Grading System for grading part conditions. You can read about it HERE