This is obviously Boss's now much celebrated OG Dual-OverDrive format - which ran from 1993 - 1998 - and who's triple-concentric-knobs plus Mode-selector controls were so successfully revived for 2017's JB-2 Angry Driver. This has sort of gained cult status in more recent years - where the 'Lead' Mode / Voicing is much loved and used - and most prefer that as a richer bassier sort of version of the DS-1 - just a much fuller and more balanced profile - it's a properly liquid distortion - and it really sings!