Use the Lines and Arrows tab in the New Dimension Style dialog box to format dimension lines, extension lines, arrowheads, and center marks.
You can set dimension line color and lineweight, specify spacing for baseline dimensions (see “Creating Baseline and Continued Dimensions”), and extend dimension lines beyond tick, oblique-stroke, and other similar arrowhead types.
You can suppress the first or second dimension line. AutoCAD determines the first and second dimension lines from the order in which you set the dimension points. For angular dimensions, the second dimension line is counterclockwise from the first. If you create a dimension by selecting an object, AutoCAD determines the first and second dimension lines based on the selected geometry.
You can also set the extension line color and lineweight, and suppress one or both extension lines. You can extend extension lines above the dimension lines and offset them from the dimension origin points, as shown in the following illustration.
The arrowhead lists provide a variety of arrowhead types that you can use for dimension lines and leaders, including arrowheads, dots, oblique strokes, and ticks. If you change the first arrowhead, AutoCAD changes the second automatically. If you want a different second arrowhead, select one in the 2nd box. You can change the arrowhead size. You can also create and use your own arrowhead symbol. See “Creating Arrowheads.”
You can change center mark settings, and change the center mark size. None turns off center marks. Marks displays center marks. Lines displays centerlines. (See “Creating Center Marks and Centerlines.”)