"It's a Greer Lightspeed clone; a transparent overdrive. Personally, I use it as a second stage overdrive (Keeley Katana -> Lightyear -> DRV or Tube Screamer -> clean amp), but it sounds great on its own with any type of amp, whether clean or cranked.
I recorded a song using this pedal, my PRS McCarty and a cranked Vox AC30, it sounded divine. When I was playing in a blues band, it was my only overdrive (using a PRS or Strat into either my Blackface Bassman or my Marshall clone, set at the edge of breakup)."