Dotco 12R91 Series Precision Governed Turbine Grinders feature high precision ball bearings for long life expectancy and require no air line lubrication. Dotco 12R91 Series Precision Governed Turbine Grinders feature a two-stage turbine motor with a roll throttle. Dotco 12R91 Series Precision Governed Turbine Grinders achieve a superb finish due to its high speed and precision spindle. Dotco 12R91 Series Precision Governed Turbine Grinders are lightweight and durable because of its composite housing. Dotco 12R91 Series Precision Governed Turbine Grinders also feature low vibration and quiet operation the minimizes operator fatigue.