Eames Shell Side Chair Herman Miller Flame Logo Help  

I've just acquired a a set of three Eames fiberglass shell side chair, all of which I am familiar with it's date and time period except for this one. It has no other marks aside from the raised HM logo and underneath it with what seems to be a Flame logo.
My internet search has resulted with no further information and I'm currently obsessed about finding out what this logo means. If anyone can shine a light or point me in the right direction I'd appreciated it!
<img class="wpforo-default-image-attachment wpforoimg" src=" http://old.designaddict.com/sites/default/files/forum/qCGIfwx.jp