In all kinds of weather, Pexco, Davidson's Flexi-Guide 400 & 500 posts are highly visible, day and night. The posts clearly delineate the edge of the roadway with bright reflective sheeting mounted on the posts at eyes level. Our post markers are durable enough for years of use in extreme cold or hot desert sun. All Flexi-Guide products are approved by the US/DOT FHWA for use on all federal highway projects.