Ultimate Ball bearings steel, 8mm 6 pcs Gen 2. The second generation of steel ball bearings are designed to deliver on accuracy, high rotational speed and high rigidity needed for the demanding conditions in a modern upgraded AEG. The 8mm steel ball bearings gen.2 have been optimized after working closely with bearing specialists. Optimized by reducing the free angle, a better steel alloy and better surface the second generation minimizes failure in your AEG. New features: Curvature in the bearing track has been optimized in order accept the continuous shock impacts from the piston in an AEG. Free angle has been minimized since no angular movement is experienced in an AEG gearbox. 7 balls has been chosen which offers less centrifugal force from each ball compared to the bigger 6 ball version = less heat and track wear in high speed conditions. Surface of the track has been optimized to minimize ball skid and heat buildup. Steel type has been optimized. We have optimized the balance between corrosion resistance and strength.