The IObanez FL9 Flanger is an analog flanger. Flange is a type of phase effect that produces a wide range of "swooshing" effects on your guitar tone.
It has your standard 1/4" inputs and outputs, AC adapter input, and red led, all in a sturdy duck yellow metal box.

Flange is a complicated effect. If you've never used one, understanding what the 4 knobs control takes a bit of experimenting. The FL9 has knobs for "delay time", "regeneration", "speed", and "width", and can be a bit daunting to master. Sometimes I create a cool sound, and then forget how to achieve it again, the tange of sounds possible and level of control is probably unmatched by any other stompbox flanger on the market. But for a devoted knob twiddler, you will be in heaven. This box is not capable of making a "bad" sound, only strange ones you may find unusable at the furthest extremes of its spectrum.

The FL9 is classic analog flange sound all the way. There is no harshness, nor thin-ness. It is a thick and warm flange, that will make your guitar warble and whoosh for days. Add in an analog delay in your signal chain, and you'll be in space cadet heaven.
I especially like the ability to dial in some Andy Summer's Police sounds, which are on the more mild side, all the way to extreme whoosh effects that make the room feel like its spinning and are unusable except just to sound wicked.

The Boss BF-2 is a simple analog flanger pedal with adjustable manual, depth, rate and res. It has a 1/4'' input and output and is not a rackable effect.

I had no problems getting this pedal working in my set up - simply plug your guitar into the input and send the output to your amp. I have not used the manual, I just use my ear and experiment with the four knobs.

The effects that can be gotten with this are wide and very useful. I use it a lot when I just looking for that extra fullness for a lead tone or if I am looking for that clean flange sound. I use it with electric guitar and keyboards.