Select grade is the premium grade and may have an occasional knot on the inside with the outside being clean. An example is shown in Figure 1.
Figure 1.
Commercial grade has tight red knots (solid knots). Woodenware is fully functional. An example is shown in Figure 2.
Figure 2.
Budget grade has black knots (may be loose). However, woodenware is fully functional. An example is shown in Figure 3.
Figure 3.