1
general::
Phrase(s): small print [and] fine print
an important part of a document that is not easily noticed because of the smallness of the printing. • You should have read the small print before signing the contract. • You should always read the fine print of an insurance policy.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Also, fine print. The details in a contract or other document, often indicating restrictions or other disadvantages. For example, Be sure you read the small print before you sign your name to it, or They had the warranty terms in fine print, so you'd overlook the fact that it was only good for a month. This idiom alludes to the fact that such material is often printed in smaller type than the rest of the document. [Mid-1900s]
American Heritage Idioms