Electrical meter ampacity rating
This would most likely be a 100A meter

The only time you ever see a 15A electric meter in North America is when it is a transformer rated meter used with instrument transformers to measure large electrical services (such as those found on large commercial, institutional, and industrial buildings).  However, this meter is a Form 1S meter, which means that it is a self-contained meter that requires no transformers to work.  (It also means that it is a 120, single phase, two wire meter, but that is neither here nor there.)  Therefore, this meter has to be a Class 100 (100A continuous, 125A peak) meter by deduction.