The spec nobody knows is the micron rating
Across our incoming quote requests, micron rating is the field left blank most often. Here is how to work it out from what you do have.
Of every specification we ask for on a quote request, micron rating is the one left blank most often. It is not carelessness. The rating is rarely printed on the element, the original purchase order is four years old, and the person holding the filter is a maintenance tech who has been handed a job, not a drawing.
You can usually get there from three other things. What the circuit drives, what the element looks like, and what failed.