The newest addition to Avery Brewing Co.’s Barrel-Aged Series is Old Grumbler, a 17.2 percent ABV blend of imperial ales aged between 12- and 24-months in rum barrels.

According to a label filed with the Alcohol and Tobacco Tax and Trade Bureau (TTB), the 55th beer in the series from the Boulder, Colo.-based brewery will be limited to 76 barrels of 12-ounce bottles and was packaged on Sept. 19.

An email to the brewery for additional information was not immediately returned.