Was looking to get a 2nd filter for our home (so we didn't have to move our 1 around the house each day) and didn't have the money for another FIT50. Turns out this FLEX is in some ways even better, especially in terms of size, looks, and value! (The cord design is better as well, the cord does not unplug from the back of the unit so can't become loose like the FIT50 could.) Fantastic value for what you get, as the filter size is nearly the same as the FIT50, and the square footage rating is close as well. The only features that are missing are the auto-setting and the ionizer, which we didn't use anyways. The 1/4 fan setting is shockingly silent, almost as if it is off. If we ever get a third filter it will be one of these!