I love Image Line's native filter plugin. This was one of the first plugins that they included with FL (me and FL go WAY back). Fruity Free Filter has got every type of filter on the planet with very reasonable sound quality. The no-frills interface eats up like ZERO cpu power. You can use it for all the typical electronic music jobs, but its also handy as hell when you just need a notch, peak, low or high shelf or to fully low or high pass a track that was recorded with a mic. I really like to use this to high pass ANY guitar I record into Fruityloops to remove rumble below about 80hz. I take a lot of care with guitar sounds and try not to EQ them, so why waste CPU and RAM on a fully featured parametric or console EQ simulation? This will take the rumble out! The bandpass can be fun for telephoning stuff too. I enjoy that all the knobs are automation friendly. Totally handy plugin. Way more useful than Fruity (not free?) Filter and the filter plugins with fancier GUIs. Gets basic jobs done quickly and efficiently.