Eureka PMF1 Foam Filter, Part # 77583-33N
As part of a good maintenance on you vacuum change it every two weeks, is washable and reusable, is always recommendable to have back ups, fits perfectly and my vacuum works like new.
What is nice is it is washable however needs avid cleaning
This is a filter you would be wise to frequently check and clean to avoid congestion in the vacume itself
This filter is provided by Crucial Vacuum and is just as good as the Eureka but much cheaper, a win win.