To be labeled as Bottled-in-Bond, a whiskey must be the product of one distillery and distilled during just one distillation season, which runs from January-June or July-December. These whiskeys must be aged for at least four years, and bottled at exactly 100 Proof, for a strong, signature flavor. Additionally, the D.S.P., or Distilled Spirits Plant numbers of both the production and bottling facilities must be stated on the label.