Straight Whiskey is created by the distillation of fermented cereal grain mash. This grain can be malted or unmalted but either way, the spirit produced from it cannot excede 80% ABV. The spirt is then required to be aged for at least two years in charred, new oak barrels and cannot excede 62.5% at the time of being placed in the barrel. Once the maturation process has been completed, the whiskey can be filtered and diluted depending on the preference of the producer however it must still be at least 40% ABV at the time of bottling.
In terms of age statements, as above, straight whiskey must be at least two years old however in addition to this, straight whiskey that is younger than 4 years old must declare its exact age. Therefore do not be put off by straight whiskeys without an age statement...unlike with Scotch Whisky, no-age-statment straight whiskeys tend to be more prestigious.