Typically used with very early model vacuum cleaners and still common on commercial machines which use ‘open ended bags’ such as backpack vacuum cleaners, where they are supported by a secondary filter ( cloth bag ) and replaced frequently.
Also still available for some older model domestic machines, but this type of bag should be changed frequently as the dust penetrates the paper filter medium readily.

Synthetic Bags

Manufactured from multiple layers of non-woven material, with welded seems (edges), these bags will provide consistently high airflow even when they are completely full.
While the level of filtration is not necessarily higher than paper filter bags, the synthetic versions are extremely durable, will not burst and are less susceptible to moisture, which easily destroys paper bags.
This type of bag is commonly included as standard with the higher value Brand machines manufactured today. At vacbagdirect our range of synthetic bags use 5 layers of material to provide superior performance,
 

Motor Inlet and Exhaust Filters

Motor inlet or ‘pre-motor’ filters are usually located in the bag compartment of a vacuum machine, they are designed to capture large debris in the event of a bag failure ( split or burst), and to protect the motor.
Exhaust filters are located in a compartment behind the motor, and filter the air leaving the machine.
Both of these filters types come in many shapes, sizes and in a range of densities.
As these filters do collect dust in the normal course of your vacuum operation, we recommend they be changed with every pack of replacement bags ( usually 5 bags ). At vacbagdirect our universal filter includes 3 pieces of filter, 1 each of ‘Fine’ , ‘Course’ and ‘Micro’ material, so you can match correctly to your machine.