[Kurri17]

I have been picking up mostly graded wax and cello packs from the '70s. However, a good bit of my childhood collection came from rack packs and I look at them on eBay and may at some point purchase some.

My question is in regards to the plastic the packs are made out of. My personal recollection is that the plastic was of the stiffer variety, and even looks to have yellowed over time, but not very flimsy looking at all. I see packs that appear very much as I remember them, but I also see packs where the plastic looks 'clearer' and just to my eye looks like a different plastic, specifically some '79 packs I have seen. Does anyone have any knowledge of what is the appropriate packaging, or did it vary through the '70s and my memory is just showing the effects of that being 38+ years ago?

Thanks for any thoughts you might have.