Launched in late 2024 to mark the 20th anniversary of Four Roses' flagship OBSV Single Barrel, the Single Barrel Collection rotates through the distillery's ten proprietary mash bill and yeast strain combinations. OBSF pairs Four Roses' high-rye "B" mash bill with its distinctively minty "F" yeast strain, aged 7-9 years and bottled at 100 proof.