Our 1x6 Douglas Fir Tongue and Groove, Select Tight Knot boards. Available in lengths 6'-16'. These versatile boards feature a v-groove on one side and a nickel gap on the other, giving you two options for a nice finish. Naturally rot-resistant and very durable, these boards are perfect for projects needing both good looks and long life. Kiln dried for strength, they ensure your vision lasts.