Frank August Case Study: 04 is the fourth release in the brand's multi-award-winning Case Study series, a creative platform for experimenting with new high-quality American whiskey expressions. This release is a blend of double-oaked Kentucky Straight Bourbon Whiskey and double-oaked Kentucky Straight Rye Whiskey. Each 4-barrel batch combines 2 double-oaked bourbon barrels and 2 double-oaked rye barrels, earning the designation "4X Oaked."

What makes this expression distinctive is the "Proofed in Barrel" process. Instead of proofing in tanks prior to bottling, water is added to bring the whiskey to 95 proof while still in the secondary barrel. Each barrel then ages an additional 12 to 14 months, allowing the spirit to continue developing complexity and depth. The result is a full-bodied and layered whiskey bottled at 95 proof (47.5% ABV).

Tasting notes reveal a deep amber appearance. The nose opens with cinnamon and dusty leather. On the palate, there is a burst of dark berries and stone fruit, followed by dark and milk chocolate, espresso beans, vanilla, banana, oak, and tobacco, all supported by black pepper and baking spice. The finish is long and warming with lingering oak, sweet caramel, and a spicy rye kick. Frank August was cofounded by Johnathan Crocker in 2022, and the whiskey is sourced from undisclosed Kentucky distilleries. Robb Report scored this release 89 out of 100.