* Large amounts of dirt dust debris pet hairs and tiny particles are lifted off your surfaces when cleaning with a vacuum cleaner and the last you want is for them to be exhausted back into the airstream. The purpose of the Post Motor Filter is to collect the dust that passes through the suction nozzle from the surface helping prevent it from being spread around your room. In addition the vacuums motor can become overheated if dust particles are not filtered out properly. If you experience a loss of suction power and you find your existing filter clogged then it is time to take advantage of this quality replacement. Your vacuum cleaners filtration system requires the post motor filter to be replaced to ensure that the environment you live in remains clean. The post motor filter should be changed every three months though it may be necessary to change it more often if there are children or pets in the home. Please check model fit list to ensure this part is correct for your model.