Until the 1950s, bottled-in-bond bourbon (also called bonded bourbon) was virtually the only kind available. Jim Beam Bonded Bourbon is a nostalgic look back at the way Bourbon used to be. The term 'Bonded' refers to 'bonded warehouses' and the laws that governed them, today 'Bonded' is used as the statement of 100 Proof (50% alc/vol). The Bourbon itself is semi sweet with dry toasted grain and oak. Light sweetness with grainy spirited fullness and aged for a minimum of 4 years.