Front,
Back, Dial, Movement,
Case mark, Closeup view of
movement
This open face Sangamo is the watch that evolved from the Grade 179. This example is housed in a silveroid case that has no extra screw marks and appears to be original to this movement.
The serial number of 1827033 places the watch in a run of hunting case movements with "Extra" marking. However, this watch is clearly an open face movement without the extra marking.
The watch does keep remarkably good time with a rate of better than 5 seconds per week in all 6 positions.