Rhetorical phrase analysis [closed]

Is there a rhetorical device found from the following phrase?

It won't cost you a thing, but it may save your life.

Solution 1:

Perhaps antithesis with cost/save and nothing/your life

antithesis (n.)

The rhetorical contrast of ideas by means of parallel arrangements of words, clauses, or sentences (as in "action, not words" or "they promised freedom and provided slavery") m-w

A figure of speech in which an opposition or contrast of ideas is expressed by parallelism of words that are the opposites of, or strongly contrasted with, each other, such as “hatred stirs up strife, but love covers all sins” Lexico