In reply to b3n99:
RPs are a very specific product, tiny wired brass nuts manufactured in small numbers by a meticulous craftsman, Roland Pauligk of Melbourne. They are so useful, so perfectly matched to the best climbers doing the best routes, that the term has become generic and is used for other brands of micro nuts.
In 1966, I was part of an incredulous group watching Roland climb his first new route in Australia after migrating from Germany. That was, I think 'Narcotic', 17 on Bundaleer, and he was partnered by Mike Stone and my friend the 'Beast' — Ian Guild.