English Made Triumph & BSA Unit Singles Rocker Box Cap Fiber Washer Set. If your Rocker Box caps have a slow pesky oil leak, put a stop to it with these great quality Fiber Washers! Just install and away you go! Inner Diameter measures 1 1/2″ & Outer Diameter measures 1 3/4″. Fits a wide range of both BSA & Triumph Unit Singles from the 1960’s-1970’s! Please refer to your parts catalog for proper fitment.****Please note that these Fiber Washers may be used for “Universal” purposes on many parts of a British motorcycle! Check the measurements abouve to ensure the best fitment!*****Made in the UKO.E.M Part number is 70-1577, E1577 or 40-0969