World Champion ACER Racing 5/32x5/16x1/8 Ceramic Ball Bearing.  This is a 5/32x5/16 ceramic ball bearing also known as a size R155 ball bearing. Diamond polished Silicon Nitride (Si3N4) Balls, HSR cage technology and sealed on both sides. Lubricated with lightweight 100% synthetic ACER Racing SIN oil, not power robbing grease, for super fast and super smooth action.   

ACER Racing lightweight ceramic ball bearings last longer and spin faster.