Why do plastic milk jugs have a circular indent on the side?

(KTXL) – Just about every plastic milk jug has a circular indent on its side, but why? Is it just decoration? Does it help determine expiration?Some people may not have ever noticed it. "Most people will go their whole lives without ever knowing what the circular indent on the side of the milk jug is for," one recent post shared to social media theorized, prompting hundreds of responses.Story continues below
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