From simple sours like the Daiquiri to lavish tiki staples like the Mai Tai, limes are an essential building block for entire categories of cocktails. But not all limes are created equal.

Contemporary cocktail recipes typically rely on the prominent Persian lime, a variety developed in 1895, confusingly, in California. Larger, thicker-skinned and juicier than Key limes, Persian limes quickly became the dominant variety, and remain the standard bearer today, largely due to their transportability and higher yield of juice per fruit.

But the smaller, tarter Key lime, a historical cocktail component, deserves a place on the backbar, too. “Because of their acidity,” explains Bobby Heugel, owner of Houston bars Anvil, The Pastry War, Tongue Cut Sparrow and Better Luck Tomorrow, “[Key limes] can balance out cocktails that use richer liqueurs, syrups or purées.”

Such is the case at Fort Lauderdale’s Mai Kai, one of the country’s oldest and most iconic tiki bars, which has relied exclusively on Key lime juice in their cocktails since opening in 1956.

“The original owners… wanted to take it up a notch, create something that was totally different,” explains Kern Mattei, the current general manager. “Key lime has a higher acidity and a stronger flavor, which actually changes the flavor of the drinks.” A central component to the Mai Kai’s original menu items, many of which are kept secret and copyrighted, Key lime juice also features in the bar’s house versions of classic formulas like the Daiquiri. But using Key lime juice, as opposed to that of Persian lime, means tweaking traditional ratios. “The acidity [of Key lime juice] reacts more with the syrups, so you have to actually use less Key lime because it’s stronger,” explains Mattei.

Huegel, meanwhile, cautions against using Key limes with certain spirits, namely dark spirits, preferring instead to let the brightness shine alongside white spirits like unaged rum, gin or blanco tequila. “Key limes, while being bolder in terms of acidity, have less texture and body,” he explains, “Thus, they tend to get covered up by barrel-aged flavors.”

In his Margarita, a fine-tuned rendition created for his Houston mezcaleria, The Pastry War, he opts for a blend of both Key and Persian lime juices. “Blending Key and Persian limes together is a powerful combo,” Huegel explains. “You get the acidity from the Key and some of the texture from the Persian.”

Put simply, it’s the best of both worlds.