Fee Brothers - Whiskey Barrel Aged BittersFee Brothers Whiskey Barrel Aged Bitters 5 oz Fee Brothers Whiskey Barrel Aged Bitters are available only once a year and we are never sure when that "once" is going to kit. So pre order yours today They age their classic aromatic bitters in Whiskey Barrels before bottling them and sendinig them to us. The aging process gives the bitters a wonderful depth you just don't get otherwise. Very unique and well worth the extra time and effort to add these