Hello! I recently acquired a bag of old technical pens — almost three full sets of Staedtler Marsmatic 700 pens, and two sets of Faber-Castell pens. I am trying to figure out how old the Marsmatics are. I've done quite a bit of web research but haven't found much info. And I have yet to find a picture online that matches my pens. The difference in mine is that they have a metal grip, some gold and some silver. All the ones I've seen online have a plastic grip, fluted or squares. I have discovered the fluted grip pens are older that the ones with the square pattern, but I would like to know where mine fall in the timeline. The image is of the six pens I've been able to clean up and get working so far. Thanks for any information anyone can provide.