The Runyon Surface Prep Non-Threaded 4.5″ Cup Wheel with 9 Segments is now quicker and more efficient. The premium 9 segment is designed to grind fast on concrete and masonry surfaces in order to remove thin set, thin mill glues, thin mil epoxies and urethanes. 9 Turbo Segmented cup wheels were designed to help reduce the “circle marks” and gouging that row style cup wheels created. Having less segments and less diamond surface area makes them more aggressive than the 18 or 24 seg version. They are the most popular option for concrete prep.