grammatical number - How do you pluralize the acronym "POC" ("proof of concept")?

What's the plural form of the acronym POC, short for proof of concept?

...for his contributions to many POCs

or

...for his contributions to many POC

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What is the correct way to pluralize an acronym? is not a duplicate as it is focused on cases like "ATMs" where the expanded form "automated teller machines" ends in a noun with a regular plural form ending in "s." In "proof of concept," the noun is in the middle of the abbreviated phrase. If we pluralize the uncontracted phrase, we get "proofs of concept," which has an "s" in the middle rather than at the end. It's unclear from the linked answers how abbreviations with this structure should be pluralized. (POC, POCs, PsOC?)

Answer

POCs is ok.

To pluralise an abbreviation (or number) just add an "s" to the end.