RURP stands for Realized Ultimate Reality Piton. They were the original thin piton for micro cracks. Today, they are very rarely used because Tomahawks and Peckers work so much better in most cases. These were used here and there until Charlie Porter place 30+ in a row on The Shield. That lead opened up the imagination of hard climbers for long, sustained and scary thing crack lines.
On 99 percent of walls, you don't need Black Diamond RURPS. I have only placed a handful in my life and they were usually on first ascents. If you are doing a hard aid route or a first ascent, bring a couple. Otherwise, the Moses Tomahawk and Black Diamond Pecker are much more effective. Tomahawks and Peckers are more secure, easier to clean, and can sometimes be used as clean aid placements.