Thanks guys, I appreciate the help on this. Jason great guide and I love the info you have added on bubbles. I really dont know much about the different types as it's not something I had ever thought about until now.
I've just started to become a lot more particular about the bubbles. So here are some of my many questions

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Large bubbles - are these tri logo bubbles? They seem a bit too large and the figure can move around too much.
Are the long bubbles also Tri Logo bubbles? Once again i ifnd the figures rattle about too much. Although i really like the ones that have a smaller upper bubble for Lando and Boushh helmets that Jason has pictures on his site.
Twin stem and double stem bubbles - They seem a bit too fragile and seem more prone to yellowing.
Medium sized bubbles without the stems seem a better size. What would you call these? I really like the way they look and they dont seem to yellow much.
I've seen people refer to US/Kenner bubbles, Palitoy bubbles and Tri Logo bubbles - how do i identify which is which?
So many bubble questions