Modern signs have several components in common. The plastic face can be Acrysteel, Plexiglas, acrylic, or one of several leading brands. The traditional sign has a retainer to hold the plastic sheet in place. Lamps run in the most economical direction: vertically for signs with center poles, horizontally for signs without. the interior electronic components come pre-assembled to your specifications on LetterBank signs. UL, the electric components standards, are common on most LetterBank electric signs, as required in many municipalities.