nope!its a seriesI all the way,however it's listed as a s/II,but from what i can observe theres nothing II about this one. the five peice wood neck through is standard for s/Is.along w/toggles this one has no master. however my series I (#12)is all seriesI physically,but has series II guts, & theres quite a few basses around with that set-up ,but nevertheless i love that bass too & looks like it came straight from john entwistle's bass line-up!