The Tone Geek ATS808 - John Mayer tones 

The ATS808 is an amazing Tube Screamer pedal, meticulously and carefully reversed-engineered to stay original to the Ibanez/Vemuram TSV808, just with more range on the bass controls and a more natural level control sweep! This a much-welcomed improvement over the standard TSV808 since the bass is usually too strong, even at the lowest setting, and the level adjustment is touchy. Ryan also externalized the DIP switches for selecting symmetrical/asymmetrical clipping and also the trim pots for bass and saturation are now on top as tiny pots for easy adjustment.
Inside you'll find a genuine OPA2134PA op-amp, 30,000 cycles rated footswitch, gold plated circuit board, hybrid SMD/thru-hole board, silver solder, "forever" power supply solid polymer capacitors, and 100 degree viewing angle LED!