an unsharpened pencil set against a piece of paper labeling approximate distances. The top of the eraser is labeled HORIZON; next are markings for 300 m, 200 m, 100 m, 50 m.
an unsharpened pencil set against a piece of paper labeling approximate distances. The top of the eraser is labeled HORIZON; next are markings for 300 m, 200 m, 100 m, 50 m.