US 1930’S AIR CORPS PILOTS “M2″ ELECTRONICALLY CONTROLLED DIRECTIONAL TRAINING DEVICE, 7 1/2″ X 6 1/2″ X 2” THICK INSTURMENT WITH GLASS DIAL ON THE TOP WITH “FLY RIGHT” AND “FLY LEFT” WITH MINATURE PLANE AT THE TIP OF NEEDLE, ONLY HM’S ARE “M2”