This is a 1900 Illinois 16 size 17 Ruby Open Face Pocket Watch that is Railroad approved. Serial # 1548361.

The Watch keeps time. It has been timed out in 6 position to within a minute a day.

 3 finger bridge, Bregurt Hairspring, Going Barrel & Micrometic Regulator.

There were only 4,270 of this style made. It is a Model 5 and Grade: 186. 

Double sunk dial has 2 very tiny cracks at 5 & 6. Lever set and stem wind.

Gold center wheel & train. 10 kt. RGP case. 

The Watch is in very good condition.