Square post with or without plate is a hollow pipe device works for holding almost kinds of wire mesh fences, such as barriers of securing highways, railways, and roads. It is made of high grade low carbon steel or rail steel, which makes it durable and can withstand the decades of damage from high wind forces and temperature changes. Zinc coating or PVC coating plays an important part in corrosion and rust resistance. So it also can be used where there is moisture and humidity.