BFP is a Barber pole Flanger Plugin to give the illusion of a continuously rising or falling flanging effect.
This illusion is more apparent at low LFO rates, but at higher rates the effect can still sound interesting.
Zip includes a paper detailing 3 proposed methods. The BFP uses 4 delay-based flangers and a 4-phase LFO. Click on the BFP label for more info about the controls.