This overdrive is like a vintage tube screamer on steroids.
They've used the JRC4558 chip which is the key to those vintage TS tones - perfect for pushing the front end of your tube amp.
But that's just the starting point, there's a lot more gain available here than a TS, and with diode and attack switches you have more control over the tone.
Everything from a front end push to a clip to full, angry gain is here - that's why it's a favorite of players like Keith Merrow and Misha Mansoor.