The mashbill of Jack Daniel's bottled in bond is 80% corn, 12% rye and 8% barley. Aged in barrels coopered in house, charred to their specifications. Fermented using their own house yeast, which they have been cultivating since the end of prohibition. Bottled in Bond whiskeys have to be aged for a minimum of 4 years, and bottled at a 100 proof (50% abv). Lots of caramel notes, rich oak and spice.