New Glarus Brewing Co. has added a new installment to its popular Thumbprint Series.

Wild Sour Ale 2018 is a sour brown ale aged in oak casks and exposed to wild yeasts for a year and a half before the final addition of Wisconsin-sourced dark malts.

The New Glarus, Wis.-based brewery’s Thumbprint Series is made up of beers chosen by master brewer Dan Carey personally chooses to brew.

According to a post on New Glarus’ Instagram page, Wild Sour Ale 2018 is available now at the brewery packaged in four-packs of 12-ounce bottles ($12.99) with no purchase limits.