For your consideration is a WWI era M-1910 canteen cup. It is in used, good condition. There are no rust or flame marks on it. There is some minor pitting on the bottom of the cup. It was manufactured by AGM CO and it is dated 1918. Interestingly it has a serial number assigned to it that is stamped on the handle.
Of course this completes your WWI canteen set. Likewise, surplus WWI M-1910 gear was used well into the early years of WWII before the war industry ramped up to meet the demands of the war.
The canteen cup is a critical, but often overlooked piece of field gear. Form fitted to the GI canteen, it is compact, lightweight and crucial for that morning cup of coffee, an evening cup of soup or as a shaving tin. The GI canteen cup is far more versatile than many comparable and expensive civilian cups.