The high wine is moved to new, charred American oak barrels, each of which hold about 53 gallons of liquid. A "bung" is used to seal the barrels before moving them to nearby hilltop rackhouses where they will age up to nine years. As the seasons change, natural weather variations expand and contract the barrel wood, allowing bourbon to seep into the barrel, and the caramelized sugars from the charred oak flavor and color the bourbon. A significant portion (known as the "angel's share") of the 53 gallons of bourbon escapes the barrel through evaporation, or stays trapped in the wood of the barrel. Jim Beam ages for at least four years, or twice as long as the government requires for a "straight" bourbon. Aging for at least 4 years also allows the distillery to legally dispense with an age statement on the bottle. At the end of the aging period the amber liquid is filtered, bottled, packaged and sent to one of many distributors around the world using the three-tier distribution system.