The Rolled Edge Vertical Line Posts have been used in California and French vineyards for decades.
Notches are on the sides in 6" increments
Standard offering is 8', 13 and 12 gauge self-colored for a natural 'wood' look in the vineyard. The heavier duty 12 gauge post is for trellis systems in high wind conditions or that will carry an extra heavy load or have wide spacing.
A typical installation will put 2' in the ground for 6' above ground.