Michter's 'Single Barrel' Straight Rye Whiskey (750 ml)Michter's US*1 Single Barrel Straight Rye Whiskey is made primarily of rye grains, though the exact amount is undisclosed. Once the grains have been fermented, they are distilled through a copper pot still. The barrels are aged in a heat cycled warehouse, which forces the wood to expand and contract in a more controlled environment. Michter's regulates the barrels and eventually decides when the whiskey has reached the companys desired flavor profile