Fee Brothers Whiskey Barrel-Aged Bitters

Fee Brothers Whiskey Barrel-Aged bitters are a common cocktail ingredient. Fee Brothers is known for its bitters that do not have alcohol in them. This does mean they may change over time, maybe even expire, although I haven't really noticed that with mine (which I've had for years). I did try a couple drops neat just to get an idea of how they tasted and it's about what you would expect, pretty bitter (especially for Fee Brother bitters), with strong whiskey undertones. As a cocktail ingredient, these come in handy quite a bit, especially for stirred old fashion cocktails. Unlike most of the Fee Brothers bitters line, these have flavor and a bit of bitterness, whereas most just taste like flavoring. Are they essential, maybe not, but I find them more useful than most.