Seam micrometers (seam mics) are small manual measurement tools typically used to measure items such as seam thickness, seam length and internal seam measurements after a teardown.
This small instrument is typically not very accurate, particularly when it comes to flexible materials such as Aluminum beverage cans. It does not ensure a specific amount of force or angle is used. In addition, it requires the operator to record its values with pen and paper.
It is recommended to use dedicated measurement gauges and to refrain from using this type of micrometer, except as a backup.