The ornamental design for a knob, as shown and described.
FIG. 1 is a front, elevation view of the invention;
FIG. 2 is a right side view thereof, the left side view being a mirror image;
FIG. 3 is a top view thereof, the bottom view being a mirror image; and,
FIG. 4 is a cross-section view taken in the direction of the arrow on line 4--4 of FIG. 1.
My knob is characterized by a frontal insert of a two dimensional orthogonally woven material whose domed shape matches the contour of the receiving knob base.