These parameters enable you to change the shape that is displayed for the null in the viewport, including its width and height as well as the general shape.
This is especially useful when you are rigging complex characters and need to be able to see the nulls clearly.
Choose the shape that is used to represent the null in the viewport. Possible shapes include Point, Circle and Pyramid (or no display - the Null Object will then only be displayed when selected).
Defines the radius of the shape that represents the null.
Defines the shape’s height as a ratio of height:width. For example, to make the pyramid shape twice the height of its width, set Aspect Ratio to 2.
Defines the orientation of the shape. Choose from Camera, XY, ZY and XZ. With the Camera setting, the shape will face the camera in all active viewports. This helps to keep the null highly visible and is especially important when it comes to character animation, where nulls play an essential part in controlling the rotation of bones.