In the Length field, you define the extent of the 2D object.
Length of extrusion
Opposite directionextrusion is carried out in the opposite direction.
Both directions: The extrusion is performed in both
directions.
Black vector = direction: against surface normal [Against surface normal]
Black vector = direction: both directions [Both directions]
Different Lengths [Different lengths]: With
this option, the 2D sketch is also extruded in both
directions, but with the ability to
define different extrusion lengths.
Enter the length perpendicular to the
surface normal in the field below " Various Lengths [Different lengths] "
(here, "30").