Blade 350 QX Quadricopter Ceramic Hybrid Upgrade Bearings Ceramic Hybrid Upgrade Bearings for Blade 350 QX Quad-rotor Kit Components: QTY.8:SR2-5C-YZZ AF2 (.125x.312x.140) Bearing Material: Stainless Steel 440C, Ball Material: Ceramic SI3N4, ABEC#1/ISOP0