yeah red arrow those air filters are very labor intensive compared to the hd filters. yes mine came from baileys with the white( small pores) and green (bigger pores) foam filters. i clean mine after each milling day. i bought the uni cleaner and oil spray cans from baileys. the cleaner works very well but is expensive. i just bought a gallon jug of simple green degreaser and it seems to work well enough. i pre oil the filters and keep them in freezer bags. i buy uni oil on amazon that isn't in aerosol form. i just dump some in the freezer bag with the filter, seal it ,then work the oil into the filter. when i get to the mill site i touch up the filter with the spray type uni oil. i just bought a new 660 in dec.2011 and did an experiment. i put my tach on the new saw and tried the stock hd filter vs. the oiled foam filter. i didn't see a giant diff. in rpms. i think in the long run though there will be a savings compared to buying stihl air filters( they really rip our jaws out on those prices) one side note. they don't come with an extra cage.(the small plastic piece that goes inside the foam filter that keeps the filter from crushing when you tighten it to the saw) i bought an extra cage at MADSENS. this way i don't have to slip filters on and off all the time.each filter has its own cage.(i just leave the cage in to clean the filters) oh yeah they take a while to dry after you clean them also. it's a good thing i don't think of my saws as tools, rather, i think of them as toys.