Hardly used Hot-Rod Plexi from Tech 21.  This is an excellent pedal with overdrive and a "Hot" switch for the extra punch.  It has an nice variety of tones.

• Based on SansAmp technology for organic tube amp distortion character
• Hot mode kicks your amp into overdrive, delivering generous amounts of preamp gain
• Tone control cuts your high-end without butchering your mids
• Punch control balances your guitar's midrange response for a killer tone
• Drive control for adjusting overall amount of gain and overdrive
• All-analog pedal design delivers smooth, natural-sounding tube character