Glenn Howerton, Rob McElhenney & Charlie Day know a thing or two about bars — after all, they've been running one on It's Always Sunny in Philadelphia for 15 seasons. Now they're helping out real-life bartenders with the release of Four Walls Whiskey. The initial release includes two expressions. The Cask Strength Single Barrel Collector's Edition is made in traditional pot stills and matured in ex-bourbon barrels for 15+ years, resulting in a highly-nuanced pour limited to just 755 bottles, each of which arrives with autographed cards from Glenn, Rob & Charlie in an engraved wooden and mirrored box. It sells for roughly $1,000 a bottle, while the Bartender's Blend mixes Irish triple distilled grain whiskey, pot still malt, and a hint of rye from Pennslyvania's Wigle Whiskey to create a versatile spirit that's ideal for mixing but can also be enjoyed neat. All proceeds from the collection go to 501c-3 non-profit organizations that benefit the bartending community.