The Flat Head FN 3XXX jeans are a 14.5oz denim woven on old shuttle looms. This denim is full of character and famous for its fast, high contrast, vertical fading. Even the pockets are designed to age uniquely, as they are specially double stitched - first with a poly-cotton thread for strength, then with a cotton thread that will shrink, leading to puckering that helps with the fading. This denim now come one-washed to take out most of the initial shrinking.
The 3009 denim is a slim-straight fit, with a medium rise and a bit of a taper below the knee. This fit is a modern straight fit that's slimmer than the 3005 but with a leg opening that works well with boots.