A unit conversion, not a quality grade
One mil is one thousandth of an inch, equal to 25.4 micrometers. Therefore 7.5 mil is 190.5 micrometers, or 0.1905 millimeters. This is only a conversion. It does not establish that a particular OptimumWrap product has that thickness.
Ask which layers are included
Does the stated thickness describe the base film, the film with coating and adhesive, or a complete stack including liner and protective sheet? Those are different measurements. The product sheet should state the scope so two values can be compared fairly.
Look for a tolerance and method
Ask whether the value is nominal or measured, what tolerance applies, and how the sample was prepared. If you are evaluating a supply batch, agree a sampling and measurement procedure rather than checking one point and treating it as a full batch result.
Bring the question into your inquiry
Send the SKU and the thickness requirement you need. Also state the application and installation considerations. Thickness is one part of the product specification; confirm the complete construction and application guidance alongside it.
References
These references explain concepts and test methods; they do not establish equivalent test results for OptimumWrap products. Confirm specifications for your selected product.