It is a 1961 Post card. There is actually two versions of this card. This is 142A, which is considered a company card. There is a 142B version with Antonelli listed as a SF Giant, that is called a box card. The box cards came, as you might guess, on the box panel of one of several different Post brand breakfast cereals. The company cards were available through the mail in sheets of 10. I do not have the box card yet.
What I am listening to: She Sells Sanctuary by The Cult