These highly durable aluminum placard holders are ideal for extreme weather or muddy conditions because they come with a removable protective shield to cover the placard while in use. Both shield and placard are secured in place by 2 stainless steel clips.
 
Placard holder is  aluminum (0.040") with clear polyethylene PETG plastic shield and stainless steel clips.
 
Replacement shields PH221 and clips FCCLIP also available