A spear is the vertical infill member of a palisade gate or fence panel. The Australian standard is 25x25x1.2 SHS in hot-dip galvanised steel, though heritage builds run 20 mm round bar for the cast-arrowhead look and commercial security builds sometimes go up to 40x40 SHS for added rigidity on taller runs.
Spears can pass through the top rail (the classic palisade look, where the spears overhang the rail by 80 to 150 mm with the decorative tip counted inside that overhang) or sit flush with the top rail (a cleaner architectural look that swaps the security read for a softer profile). At the bottom, three options apply: through-bottom (a short 25 to 100 mm spike below the rail, the heritage fence-line look), flush-with-bottom (the shaft ends at the bottom rail), or cut-into-bottom (the shaft sits on top of the bottom rail and is welded along the rail line, which keeps the swept envelope clear of wheels on a sliding gate or the driveway on a swing gate).
Spear spacing is the lever that controls how the gate reads from the street. 100 mm face-to-face spacing reads as a tight security fence. 150 mm reads as decorative. Below 100 mm starts to feel oppressive. CAD60's spear-top models take spacing or count as direct inputs and redraw every spear in the front elevation in real time.