Mike Tyson’s return to boxing against Jake Paul is set to be one of the biggest sports betting events of the year — except for gamblers in several US states.

Of the 38 US states to have legalized gambling, at least six have banned sportsbooks from accepting bets on the fight. Bettors in New York, Pennsylvania, Colorado, Kentucky, Louisiana, and Vermont will not be allowed to place any legal wagers on the contest.

The ban is due to the fight’s non-standard rules. While the Texas Department of Licensing and Regulations classified the match as an official heavyweight fight, the rounds will last for two minutes instead of three, and 14-oz gloves will be used instead of 10-oz ones.

the Pennsylvania Gaming Control Board said the fight was “more of an exhibition”

As a result, many state gaming authorities have chosen to prohibit any legal sportsbooks from accepting bets. Speaking to USA Today, a spokesperson for the Pennsylvania Gaming Control Board said the fight was “more of an exhibition.” Meanwhile, a spokesperson from the Colorado Department of Revenue stated the match “does not meet the minimum requirements for the industry in the state.”

Current betting lines at FanDuel have Paul as a -205 favorite, with Tyson offered at +168. BetMGM stated that they expect the fight to generate the most money wagered for any boxing match in the history of the sportsbook.