Duet of 6L6-GE tubes rated from power range 1-10. Faithful reproduction of original ''clear top'' '50s and '60s tubes. Each duet is matched and biased to a specific output level (R2, R7, etc.). R1-R3 - Low: Early distortion, wide range, softer attack good for Rock and Blues solos. R4-R7 - Medium: Normal performance, great dynamic range/attack and best all around rating type for all styles of playing. R8-R10 - High: Most dynamic range, most clean power/less break-up for power players, Jazz and bass amps.