Brooklyn Hemispherical Rhubarb Bitters
From the BHB website:
Our bitters are made in the classic style, drawing flavors from roots, vegetables, fruits, and herbs. All our bitters are carefully crafted by hand in Brooklyn, using local ingredients whenever possible. The bitters are created seasonally. When a key ingredient in a particular bitter goes out of season we won’t produce more until the season returns; we will run out of stock on flavors throughout the year. But they’ll be back.
This is a 4 oz bottle with dropper.