The DiMarzio John Petrucci Pickup set contains 2 well-designed pickups: the LiquiFire (neck) pickup and the Crunch Lab (bridge) pickup. Easy to install, they"ll bring a collection of powerful rock tones to your guitar while reducing noise. Two sizes of pairs are available: the 42mm is for normal spacing and the 43mm is for Floyd Rose and other wide-spaced tremolo bridges. LiquiFire (neck) One thing has stayed consistent throughout John Petrucci"s long and successful career: the DiMarzio pickups in his guitars. John has been pushing the envelope of progressive metal since the late eighties, and the DiMarzio LiquiFire Neck Model resulted from the most recent collaboration with John. He used it throughout Dream Theater"s tenth studio album, "Black Clouds & Silver Linings." John swears this is the best live and studio sound he has ever had. He wanted a neck pickup with a flowing, singing solo tone when used with a heavily overdriven amp and a clear chord sound with a clean amp setting. Since the mid 1990s, John"s neck pickup sound has been based on either the standard Air Norton or the custom version in his Ernie Ball guitars. The LiquiFire has several significant differences. Its treble response is warmer and smoother while bass response is tighter and brighter. The total sound has a more focused voice which works equally well for highly overdriven solos and complex, clean chords. Crunch Lab (bridge) The DiMarzio Crunch Lab Bridge Model ensued from the most recent collaboration with John. He used it throughout Dream Theater"s tenth studio album, Black Clouds & Silver Linings as well. John swears this is the best live and studio sound he has ever had, and the name says it all - "crunch" is what it"s all about with a big, tight sound that"s neither muddy nor thin. The Crunch Lab is noteworthy for what it doesn"t do - it"s not a screamer, and it"s not about thundering lows. It"s louder, and the highs have more depth. The lows and mids are more open, and this is crucial for playing chords with body and presence through a gained-out amp. The voicing of the pickup is also different enough to the point that John prefers the Crunch Lab to be installed in almost all of his guitars (including the JP Bari) with the solid bar toward the neck, regardless of the guitar"s tuning.Powerful collection of rock pickup tones Quiet performance Great value