I bought them with a project car/motor. I don't know their history, specs, or functionality. They seem to be an older model as I can't find any info on them. I also emailed Edelbrock with no help from them. They said they're RPM heads when I don't believe they are. They have 1.90 valves. They have EO D-215-16, and 6025 above the springs. They come with everything pictured. Sold as is.