They are a mid-late 80's thing,i'm not sure on the rareness of them as i have seen them around on a few occasions at shows and even bought cars with them stuffed down the backs.I just sold a set on ebay with the bag and fitting instructions for £26 they also looked like they'd never been used.So there you go mate probably worth keeping for what your going to get for them,i only sold mine because i knew i would never use them and probably lose them at some point.