1/8" Thick. Strong. This is also know as a sandwich board. Consists of two aluminum skins on the outside, and compressed PVC in the center.
1/4" Thick. Much stronger and heavier than 3 mil. Comes with two grommets on top, and is direct to print with UV inks.
1/2" Thick Wood. Heavy duty, medium density overlay, specialty treated to survive the rain, snow and heat. Direct to print with UV inks, comes with two holes on top.