Clear Grade - Clear grade pine is generally sold as Rift or Vertical Grain. It is virtually knot free and has near 100% heart content. Select/Better Grade - Near 100% heart content with a mixed grain pattern that includes up to 75% vertical grain. Dense grain: 8 growth rings per inch minimum. 80% knot free. Cabin Grade - Variable heart content, mixed grain pattern and density. High knot content. This grade is the most rustic of the available grades.