Tequila producers are playing a bit of catch up in the aging game. Until recently, tequila wasn’t known for a long maturation process. Unlike whiskeys, which often boast about the amount of time the liquid matures in an oak barrel in a process meant to improve taste, most tequilas sit in barrels for just a year or two. But makers of Mexico’s famed spirit have experimented by leaving the beverage in oak barrels longer, a process that results in a different flavor and color for the drink, which goes into the barrel clear but turns an amber or brown hue depending on how long it matures.

Some tequila producers have increasingly boasted about their highly aged drinks, which come with a hefty price tag and limited volume — a successful strategy the whiskey industry has relied on for years. High-priced tequilas have posted stronger sales than the cheaper stuff, helping boost the category’s supplier revenue to more than $2.1 billion last year in the U.S., according to the Distilled Spirits Council of the United States.

Patron and Pernod Ricard are among the tequila producers leading the age-statement charge. Conversely, some Scotch makers are shying away from adding age statements to their bottles, likely reacting to stock shortages as demand for the drink has increased.

Earlier this month, Patron caught the industry’s attention when it announced the debut of a seven-year-old Extra Añejo. It is the oldest tequila the company has ever produced, aged far longer than the three-year requirement necessary to call the liquid by that name. The price? $299 for each bottle.

“At seven years, we felt that it was perfect for us,” Patron distiller Antonio Rodriguez told Fortune. “We didn’t want to go further because we were worried about losing the agave flavor.”

In selling aged tequilas, distillers are betting on smaller batches that come with lofty price tags. That mirrors a broader trend in the spirits industry, which aims to “premiumize” brand perception with limited productions of new concoctions, while also talking about a brand’s heritage. Tequila producers are also benefiting from rising interest in the spirit, which posted a 5% increase in U.S. sales volume last year, besting all spirits categories with the exception of whiskey.

Tequila producers have a distinct disadvantage when it comes to aging their spirit. All tequilas are made from the blue agave plant, which takes at least seven years to grow before it can be harvested. The various grains used in whiskeys take far less time to pull from the ground.

That hasn’t deterred Patron. The company said it was able to mature the tequila for seven years by placing barrels in the coolest part of its warehouses at the Hacienda Patron distillery in Jalisco, Mexico. The low-to-ground position of the barrels, as well as the atmospheric temperatures between 2007 and 2014, led to the ideal conditions needed to age the spirit without losing the agave flavor.

“Even if we tried to replicate Patron Extra Añejo 7 Años, I don’t think we’d ever achieve the exact same result,” said Patron’s Master Distiller Francisco Alcaraz. “In my 40 years in the tequila industry, I’ve never seen a tequila aged this long taste this good. This is equivalent to a rare 50-year-old Scotch.”

The company only produced about 9,000 bottles of the aged tequila, and has no other barrels in the pipeline with which it can produce more, said Rodriguez. The company is working on some other innovations, but none with the same lengthy time frame, he added.

Avion Spirits LLC, a tequila that’s majority controlled by French beverage giant Pernod Ricard, ages its tequilas beyond the industry norms. The company’s Reposado is three times older, while the Anejo is aged twice as long. The Reserva 44 is aged for nearly four years, more than the three years required for the Extra Añejo.

“This has become the Pappy Van Winkle of tequila,” said Ken Austin, Avion’s founder and chairman, in a reference to a bourbon that is extremely difficult to find. Austin, who signs the label on every bottle of Reserva 44 sold by Avion, called inventory “limited” even as the company is in the process of bottling more of the liquid.

Avion, which launched in July 2010, is playing a little catch up when it comes to the age statement game, with Austin indicating he’d like to bottle tequilas that are even older than Reserva 44. The company is testing various aged tequilas, as well as putting the liquid in different barrels produced in Europe.

“We have product right now in barrels, I’m catching up,” Austin said. “I didn’t start long enough ago that I can say ‘I have something that’s 8 years old.'”