6" x 72" Heavy Duty Flex-Bollard Sign System for Asphalt6" X 72" Heavy Duty Flex Bollard Sign System For Asphalt Heavy Duty FlexPost Sign System For stronger signage, the Heavy Duty Flexible Sign System is right for you. Manufactured from cast steel and galvanized coated with an integral 5 16" diameter spring, the heavy duty flexible sign system comes with zinc coated anchors for asphalt or concrete installation, which only allows it to move when contacted by a vehicle. It's also so trusted and tried that