The ornamental design for the rotary laser unit, as shown and described.
FIG. 1 is a top left perspective view of one embodiment of the rotary laser unit;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a top view thereof; and
FIG. 7 is a bottom view thereof.
FIG. 8 is a top left perspective view of another embodiment of the rotary laser unit;
FIG. 9 is a front view thereof;
FIG. 10 is a rear view thereof;
FIG. 11 is a right side view thereof;
FIG. 12 is a left side view thereof;
FIG. 13 is a top view thereof; and,
FIG. 14 is a bottom view thereof.
Elements shown in the drawings in broken or phantom lines form no part of the claimed design, and merely illustrate the environment in which the article embodying the design is used.