The sanders are balanced to achieve an equilibrium between the reaction force from cutting and the excentricity of the pad versus the shaft. This relation generates a minimum of vibrations when correct feed force is appli......The sanders are balanced to achieve an equilibrium between the reaction force from cutting and the excentricity of the pad versus the shaft. This relation generates a minimum of vibrations when correct feed force is applied. Lubrication free Avoids contamination of workpiece. No oil in the exhaust air.