Test apparatus for either counting mesh or measuring irregular openings shall be compatible with the value of the tolerances.
Examples of test apparatus to count mesh include a counting glass and a standard metal rule .
Examples of test apparatus to measure openings include a graduated magnifying device, a vernier inside caliper, and a standard metal rule.
All test apparatus shall be calibrated against standards traceable to the National Institute of Standards and Technology
Counting Glass
Standard Metal Rule
Vernier Caliper
Micrometer
