Chaincase inspection cap assembly for steel primary chaincases.  Has correct style 014357 slotted and knurled screw, used from 1949.  Backplate is painted black, as original, and fitted with a leather sealing washer. 

These are New Old Stock from Domiracer.  They are not flawless - the paintwork isn't perfect and the chrome is tarnished - but they are authentic looking, perfect for original and unrestored models.