Its a Trap - sorry Its a vaccum guage, was watching Big Bang theory, ' just imagine me with a squid head'. It's amazing yours still lights up, though I think your missing the yellow section. It's just another holdover from the late seventies, early eighties when vaccum guages were touted as the next best thing in fuel economy, the longer it's green the better the economy. I had the same thing in a 1978 120y, but that was purely a guage. It's amazing how quickly that guage used to go to bad economy,maybe I shouldn't have been driving in my work boots.