The wharehouse where the mature Jack has probably about 17 levels that hold the barrels. The first 2 levels which stay the coolest since heat rises is where the Green Label comes from. Since this level does not get as hot the barrel does not expand and contract as much and therefore the liquor does not go into the pours and absorb the vanilla oak flavor from the barrel. Level 3 through through 15 are your standard black label and the upper levels are Single Barrel Jack.