Michter's US*1 Single Barrel Straight Rye Whiskey is made from a mash comprised primarily of fresh, plump rye grains. Once the grains are harvested, they are sheared so that during fermentation, the grains are saturated with more flavor. After the grains have been fermented, they are distilled through a copper-pot still before being matured in charred, American oak barrels. The barrels are allowed to rest in a heat-cycled warehouse, which forces the wood to expand and contract as the temperature rises and falls. This heat cycling causes the whiskey and wood to mingle with each other, and contributes notes of marmalade and light caramel to the rye.