This is a brand new 12 volt Lucas RF95 regulator, as used on MG TC, Jaguar XK120, Alvis and other quality cars of the 1940s and 1950s. The RF95 featured built-in fuses, and even included a pair of spare ones clipped to the cover, as the pictures show.
This regulator was made in England on the original Lucas tooling, although the parent company of Lucas, TRW, no longer permits the Lucas name to be printed on these products, as they are no longer produced by Lucas. It is a high quality part, beautifully made.
We have numerous secondhand RF 95 regulators in stock and offer a rebuilding service. We even have one that is made for 6 volt operation. Contact us about one of those.