Sorry for another traffic light thread, but I'm quickly getting bored.
Anyway, what brand of traffic light does your state use? Missouri has used Eagle Durasigs for a while now (with smooth raised circles on the back, see here (https://www.google.pl/maps/@38.6312559,-90.4436094,3a,26.3y,348.74h,104.58t/data=!3m6!1e1!3m4!1skiWU3I32kxRjejSW-vErTg!2e0!7i13312!8i6656/)), but newer installs use Econolite Poly Buttonback (as shown here (https://www.google.pl/maps/@38.6624613,-90.4052072,3a,75y,182.44h,121.09t/data=!3m6!1e1!3m4!1s81mF9ojCviTR38l8a_8noA!2e0!7i16384!8i8192/)). I know California mostly uses McCains (https://www.google.pl/maps/@34.0060105,-117.5026342,3a,51.2y,295.8h,103.32t/data=!3m6!1e1!3m4!1sl0-ACy2c42a22lnV1jRZ3Q!2e0!7i16384!8i8192/), with a few Econolite bullseyes (https://www.google.pl/maps/@33.9749934,-118.2520099,3a,34.8y,190.83h,109.78t/data=!3m6!1e1!3m4!1saF7vknUs15RYxlDPx822gw!2e0!7i16384!8i8192/) on older signals.
What do your states use?