profile lenght

Hello,
unfortunately I don't know the application from which the images comes.
Is it in Modeling, Annotation, Modelmanager or what?
General recommendation: right click in the yellow input field and see what is offered there.
Often there are measurement functions.

Have a nice day 😉

you can 

• inquire the part's box size using Integration KIT function sd-inq-exact-box 
• subtract the start and end point  (both are 3D Vectors) using Integration Kit function sd-vec-subtract 
• and take the maximum  using common LISP function:  (max delta-x delta-y delta-z)

if you do not have a small piece of a profile with a large cross-section it will work in many case.