Check this field if there is a cylindrical section attached to the expansion joint at the OD. This will always be true when you have an expansion joint with only a half convolute (1 FSE). It may also be true when there is a relatively long cylindrical portion between two half convolutes, as in the case of certain inlet nozzle geometries for heat exchangers.
See the figure in Expansion Joint Inside Diameter. Click 
to open the Outer Cylinder Dialog Box and define more properties.