Use of orange fluorescent sheeting on STOP/SLOW paddles

Iowa requires the use of the florescent orange sheeting on the STOP/SLOW paddles for two-lane roadways.
Iowa DOT’s GENERAL SUPPLEMENTAL SPECIFICATIONS for CONSTRUCTION PROJECTS says:
“STOP/SLOW and SLOW/SLOW paddles shall use Type VII (Iowa) retroreflective sheeting. The black legend shall be accomplished with black nonreflective sheeting that is direct applied or silk screened with black opaque ink. The white legend shall be accomplished with transparent red ink that is reverse silk screened on white Type VII (Iowa) retroreflective sheeting.”