This Microfilter set fits the Airblet D series Sebo Canisters. This filter set includes one exhaust micro filter and one pre-motor protection filter. 

The Motor Protection Filter is the pre-motor filter, that cleans the air passed through the filter bag, before it passes over the vacuum motor.  The exhause microfilter is designed to attract and capture dust and allergen particles from the airflow of the vacuum after it passes over the motor to cool it.