Antique Stereoscope Viewer w/+200 Photos -WWI, Europe, and Australia c1900-1920 For Sale

This 100 year old stereoscope works with a slightly dusty 3D viewer and over 200 stereoscopic cards in great condition. The viewer and set from the Monarch/ Keystone View Co. Photos are dated between 1901-1915. Half of the photos are from The Great War (World War I,) and other half are scenes from around the world. These photos show amazing moments from life in the beginning of the 20th century. Photos range from trench warfare and military arsenal, to the Zeppelin crash site, to Highlander troops in 1901, to horse and buggy street scenes, and to many historic landmarks.
Item works, but has some tattered leather and is dusty. The binders that hold the cards have lost parts of their original binding, but the cards are in great shape.