A fleur-de-lis head has a tall centre petal and two curled side petals above a binding band. It is a flat casting, so it is wide in the plane of the gate and thin through it, and it is fixed to the top of the shaft by welding or a spigot.
Because the head is a casting, the shaft is cut to its own length and the head is listed separately as a bought item. The width of the head matters for spacing: a head wider than the gap between shafts will clash with its neighbour, so the face-to-face gap has to stay larger than the head's overhang on each side.
The fleur-de-lis is a traditional heritage choice and is usually used on every spear of a run, or on every second or third spear in a puppy-picket pattern.