50% ABV

About Bottled in Bond Spirits
The Bottled in Bond Act of 1897 was passed as a response to the widespread adulteration of American Whiskey and the sale of illicit, untaxed and unregulated spirits at the time. It was meant to be a guarantor of quality production methods and aging and provided tax incentives to producers. Spirits labeled Bottled in Bond must be the product of one distillation season from one distiller at one distillery. It must be aged in a federally bonded warehouse for a minimum of 4 years and bottled at 50% ABV or 100 proof. The product's label must identify the distillery where it was distilled and bottled. 

For us it is a marker of sufficient aging and robust alcoholic strength. Bonded spirits are almost always excellent for use in cocktails due to their higher alcoholic strength which can stand up to dilution and mixing with other ingredients and flavors.