A collaboration combining the talents of Jester King Brewery and American Solera that began its journey almost four years ago is finally ready to be released.

The two breweries have joined forces on Coolship Roadtrip, a 100 percent spontaneously fermented blend made up of ales from three years that were aged in barrels. Essentially, once a year since Feb. 2016, Jester King has taken wort from its brewery that had been left in its coolship overnight and drove it to Prairie Artisan Ales—where American Solera owner Chase Healy was working before opening American Solera—where that ale was put into barrels for spontaneous fermentation. The process was then reversed, with wort from American Solera was driven down to Austin, Texas and put into oak barrels at Jester King.

“At its core, Coolship Roadtrip is a culture swap based on the concept of microbial terroir. We wanted to take microbes from Texas, send them up the road to Oklahoma, and see what sort of beer they’d produce (and vice versa),” reads a post on Jester King’s website. “The impact that microclimates have on spontaneous fermentation intrigues us and is the philosophical heart of this beer.”

Traditionally used in Belgium, a coolship is a large, shallow steel pan about a foot deep that is used to both cool down wort after it is brewed and to expose the resulting concoction to naturally occurring yeasts and bacteria that are in the air.

According to a post on Jester King’s Facebook page, approximately 1,400 375ml bottles ($20) of Coolship Roadtrip will be available when it goes on sale today with a purchase limit of three bottles per person.