Insert or Move Size Label
To insert or move a size label for a pipe on the drawing, go to
Ribbon: 
Insert or Move Size Label
Pulldown Menu:
You will be prompted to select the pipe for which the size label is to be inserted or moved.
Select pipe label to move:
You will then be prompted for the location of the size label.
Right-click or press space to toggle the leader on or off. Press "L" to move leader endpoint.
Specify a point on the drawing or press ENTER to insert or move the size label.
Type L to move the end of the leader along the pipe. Type L again to specify the location of the label.
See the Inserting Notes and Leaders on the Drawing section for more information about inserting the size label.
Stack fractions: Sets how fractions in labels are displayed.
Horizontal and Vertical pipe leader arrow blocks: Sets the blocks used for leader arrows.
These options can be further customized with the Horizontal and Vertical pipe leader arrow size options.