Billboard modification and retrofit

To develop a simple method of modifying billboards to accommodate face mounted gripper bars versus wrapping around the structure.

[@jorah342]

What is a retrofit?

[@rootstockdesigninc.717]

Modifying an old preexisting billboard structure with updated posting technologies

[@I_am_superman]

What size post should i use if i want erect a steel 9m x 3m billboard at 2.5m high frm ground
1. For unipole ?
2. 2 pole ?
3. 3 pole ?
4. 4 pole ?