NOS (brand new / unused) electro-mechanical alternating sign flasher. Great Lakes / Signatrol Model 30-A2. This is a genuine Signatrol alterating flasher manufactured by Signatrol, in the 1990's, before they were bought out by Great Lakes. It is the same flasher used by Federal Signal in their RC6 and RCM3 controls for the Thunderbolt 1003 and 3T22. It is in perfect, time-capsule condition! Thanks for looking!