Each reducing washer is stamped with trade size information for ease of product identification; For use when a raceway is smaller in trade size than the trade size of the knock-out it is intended to enter
Standard
UL 514B, UL File Number E148715, US Federal Specification Number A-A-50553, NEMA/ANSI FB-1, Military Specification Number W-F-406D, W-F-406E, W-F-408D, W-S-610D