What is the difference between Amcon Tear Flow Test Strips and standard Schirmer Tear Test Strips?

"Amcon

Amcon Tear Flow Test Strips (PO-5400) are Schirmer strips that feature a printed metric scale for unmistakable interpretation.

Standard Schirmer Tear Test Strips (PO-6394) do not have a printed scale on each strip, so an additional metric ruler is needed for test interpretation.