Yeah it's just another boring BOSS pedal, right? And it's purple, or fuchsia, or whatever... But it is yet another example where BOSS does something, and does it so well, that everything else is now compared to it. The BF-2 Flanger is a classic, and for good reason. It sounds awesome. There is a wide range of sounds, easily dialed in, going from a full-on psychedelic wobble, to a 747-soaring overhead, to a soft chorus-like blend. If you want to flange, there are plenty of options, but not a better one.
I use this on my bass for the Tool/Justin Chancellor sound, which is not surprising as he uses the same exact pedal.
BOSS BF-2 Flanger
Standard size BOSS effects pedal, usually colored purple, that produces several flanger and chorus-type effects.