Bezier curvature and Tangent dimension tools are two of the most unique tools in CADtools, measuring complex curves for proper reference in manufacturing.

Bezier curvature dimension
First create a Bezier line with the Illustrator pen tool. Select the Bezier curvature dimension tool and position the cursor directly over the path. Click and drag along the path to see the radius and its arc at every point. Release the mouse at the desired point to finish the dimension. To hide the arc, hold down the control key while dragging.

Tangent dimension
This tool works much like the Bezier curvature dimension tool, except that the tangent is created at the selected point along the path. First create a Bezier line with the Illustrator pen tool. Select the Tangent dimension tool and position the cursor directly over the path. Click and drag along the path to see the tangent at every point. Release the mouse at the desired point to finish the dimension. To show the normal (perpendicular), hold down the shift key while dragging. To show the normal without the tangent line, hold down the shift and alt/option keys while dragging.