The use of the extension is optional.

It is a section between the azimuth base and the mast/post.

Used to raise the height of the dish, which may help avoid line of sight obstacles.

Also used during the setup to raise the height of the levels for easier viewing.

Azimuth Base	Azimuth Ring	Calibrating Azimuth
Calibrating Elevation	Extension	Line of Sight
Line of Sight Tool	LNB	LNBF
Mast	Mast/Post	OD
Plumb	Satellite Dish	Skew/Tilt