be an advertisement for something
From Longman Dictionary of Contemporary Englishbe an advertisement for somethingbe an advertisement for somethingIMPRESSto be a good example of something or show how effective it can be He’s a very good advertisement for the benefits of regular exercise. → advertisementExamples from the Corpusbe an advertisement for something• Ben is a walking advertisement for the benefits of regular exercise.• This is an advertisement for handguns.