The Ethos TWE-1 Overdrive is a compact version of a family of preamps, built by manufacturer Custom Tone, that got progressively smaller – you can find them all here. The soundbite the company uses to present this stompbox is “Clean-to-Scream with just the turn of your guitar’s volume control” – which is pretty appealing.
TWE charmingly stands for “Train Wreck Express.”
Check out this video by Shawn Tubbs:
And here’s Mike Hermans take on it: