Well, I should have known better, I've made this mistake before, just did it again. I wanted to put new air filters on the two 026s if traded for recently. One had a bad looking mesh filter, the other a dirty, but probably still usable, fleece covered one. Someone here recommended that I purchase the "fleece" type ones, better than mesh, makes sense. When I checked OEM Stihl on ebay, they were about $35 each! Man $70 for two new filters. I looked around and saw very similiar looking aftermarket ones being sold all over for about 12-$16. So I ordered two aftermarket ones. Was all excited when my mail lady delivered them today. Headed right out to the garage, took off the old Stihl filters and tossed them in the trash, and installed the spanking new beautiful filters on the two 026s. I had installed a new adjustable oiler on the one saw and was waiting for the new filters to arrive to try cutting with it. I headed out back to a nice beech top and started it up......... at least I tried to start it up that is. It would cough, sputter, run a little and die. Tried everything, no luck, it was not going to run. I went back to the shop and started tinkering with it, and started thinking about that new filter. So I took it off and started the saw up with no filter on it..............it ran like the devil. I tried starting up the second 026, it would run, but very rough and would quit if I tried to give it throttle. Obvious problem with the cheap filters. I retrieved the two old Stihl filters out of the trash, cleaned them up as good as possible, and put them back on the saws. Both saws ran perfect. A close look with a big magnifying glass at the aftermarket ones shows a type of coating that looks like it has sealed the surface not letting much air through. Lesson learned............................ again. You get what you pay for.