49 C.F.R. § 236.810 Spectacle, semaphore arm.
Title 49 - Transportation
That part of a semaphore arm which holds the roundels and to which the blade is fastened.
Title 49: Transportation
PART 236—RULES, STANDARDS, AND INSTRUCTIONS GOVERNING THE INSTALLATION, INSPECTION, MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES
Subpart G—Definitions
§ 236.810 Spectacle, semaphore arm.