Manhattan Prep’s 4th Edition GRE Strategy Guides have been redesigned with the student in mind. With updated content and new practice problems, they are the richest, most content-driven GRE materials on the market. Manhattan Prep’s 4th Edition GRE Strategy Guides have been redesigned with the student in mind. With updated content and new practice problems, they are the richest, most content-driven GRE materials on the market.