Four hockey fans in Idaho are suing a local arena after they discovered that a “large beer” and “small beer” sold at concession stands contained the same amount of liquid.

According to the lawsuit, concessionaires at CenturyLink Arena in Boise knowingly sold beer in two different-sized cups at different prices despite the fact that they had no actual difference in volume, the Associated Press reports. A shorter, wider beer sold for $4, while a taller, narrow cup of beer was marketed as a “large” and sold for $7.

"While different shapes, both cup sizes hold substantially the same amount of liquid and are not large versus small in actual capacity," attorney Wyatt Johnson said in the lawsuit. "Defendants knowingly sold each of their beers in a similar manner at each event held at the arena where beer was sold for at least the last five years."

The plaintiffs -- William Graham, Brittany Graham, Brady Peck and Michele Bonds -- are seeking $10,000 in damages, AP notes. Peck claims to have purchased beer at CenturyLink Arena at least 30 times in the last three years.

The difference, or lack thereof, in the arena’s beer sizes came to light after a pair of fans posted a video of an experiment to YouTube, the Idaho Statesman reports. Gwen Gibbs and Heath Forsey, who attended an Idaho Steelheads game at CenturyLink Arena last Saturday, tested their theory by pouring the beer from a “small” cup into a “large” cup. The liquid reached the top of each receptacle.

"It's amazing what can be done with one little video and the power of social media," Gibbs told the newspaper. After learning of the video, Eric Trapp, president of the Steelheads and of CenturyLink Arena, released a statement via the team’s Facebook page.

“It was recently brought to our attention that the amount of beer that fits in our large (20-oz) cups also fits in our regular (16-oz) cups,” the statement said. “The differentiation in the size of the two cups is too small. To correct that problem, we’re purchasing new cups for the large beers that will hold 24 ounces, instead of 20, for the remainder of this season to provide better value to our fans. As we do every offseason, we’ll evaluate our entire concessions menu for next season over the summer.”

In addition to hosting games for the ECHL’s Steelheads, CenturyLink Arena is the home of the NBA D-League’s Idaho Stampede.