The Purple like all MkIII's is a MkIII. It is the second in the stripe series coming after the short lived "black dot". Probably IMO the most noticable thing is that is has somewhat less gain in R1. R2 is also voiced to be "rounder" and has less gain than the subsequent Red Stripe. Still great sounding amps with very minor differences than the other stripes. Any MkIII is a good score.