Shortbarrel Four Grain is a bourbon bottled at 46% ABV. As a bourbon, it is made primarily from corn and matured in new charred oak, a style typically associated with notes of vanilla, caramel, and oak spice.
The "four grain" label indicates a mashbill built from four different grains rather than the more common two or three. For newer whisky drinkers, that usually suggests a bourbon style that may show layered sweetness, grain character, and spice rather than focusing on just one note.
Whisky Advocate