This is not an exact copy of a Rat pedal, but it gets you there if you fiddle with it. Main reason it is not "drop on your face" rat copy, is that this is much more versatile. If you want a decent distortion with many sounds inside, this is for you. Filter knob does magic and the Type of distortion switch is also very useful. Adds a lot to the choice to the tone. And for this price? Seriously? It is phenomenal for me to think that someone can build this so cheap, considering the retail price, factory cost must be ~10-13Eur. TC Electronic gear is fantastic for what they sell it for (I've got Delay, Reverb - had a few overdrives as well. All very, very decent pedals).
Build quality is flawless - the construction is all metal. Very rugged. It is super, super small as well - about 1/5 smaller than a Nano big muff. It will fit any pedalboard.
The availability is not great - I ordered it ~6 months ago and received just now. Not a deal breaker for me, but if it is out of stock, you could be waiting for months.