Pre-motor Filters � Pre-motor filters clean suction air after it passes through the filter bag, but before it passes over the vacuum motor. Cooling the motor with clean air is important because this increases useful life expectancy.
S-class Exhaust Microfilters � S-class Exhaust Microfilters (S = �Schwebstoff� = airborne particles) are made from electrostatically charged micro-fiber material, which attracts and captures dust particles from the airflow of the vacuum after it passes over the motor to cool it. This means that exhaust air is cleaned to the highest level. The S-class Standard requires filters to absorb greater than 99.9% of particles down to 0.3 microns in diameter. For comparison, 100 microns is the diameter of a human hair. Their advantages are a relatively open texture that allows smoother airflow for better suction performance, a longer life expectancy, and they cost less than HEPA filters.