The T Riders Union is coming out swinging in its battle against fare hikes on the MBTA.

Hoping to inspire contenders at a Tuesday night hearing (5-7 p.m.) on raising fees by an average of about 7 or about 10 percent system-wide, TRU on Monday publicized a boxing pun-laden promo calling on advocates to “knock out the fare hikes.”

“Float like a fare increase, sting like a fee,” it reads, advertising “all seats now up to 23.1 percent more” and saying it’s “a matchup 16 years in the making.”

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The boxing match imagery just makes sense as activists step in the ring with the heavyweight MBTA, said T Riders Union community organizer Caroline Casey told Metro.

“The way we see it, the Baker Administration threw the first punch. We’re here to challenge them to a fair fight,” Casey said in an email, adding that there are “thousands of riders who simply can’t afford another round of hikes and cuts.”

The union believes higher fares aren’t needed to close a budget deficit, that the T shouldn’t be able to raise fares by 10 percent and that monthly passes shouldn’t go up by a larger percentage than per-ride fees, she said.