Modified PRS? More like a redesign of the PRS concept. Half pound lighter and everything locks into place solid. Really impressed with this stock. If you are a "knuckle dragged" and need an extra long length of pull, they give you additional spacers. I'm 6'01" with pretty long arms and didn't need the spacers, but nice to have them just in case. I think you can get the stock alone for around $130.