Help with explaining different infusion sets for tandem

I have mostly used the auto set 90 with my tslim but came across info about different sets for different areas and different cannula lengths. Can anyone help explain this to me? I have had T1 for 36 years now so most likely scar tissue though I can’t feel it. I read that can impact the cannula length?
Thanks everyone

@Spooky typical infusion sets are straight (90 degrees) angled, and steel. The straight sets come in, typically 6mm and 9mm. The angled sets are longer… because they are angled. If you don’t mind advice, get your sales rep and ask for samples of all of the infusion sets and try them.

Generally speaking the shorter sets are good for people who are lean, while the longer ones are for those of us who have a little more meat on our bones. But there are no hard and fast rules as to what type or length to get. I’ve used both the 90 and the 30, and personally found the 90 a bit awkward to unwind and insert, so ease of use is a factor as well. That said, I liked to switch things up now and then, thinking different angles might help prevent scar tissue: that was just a thought in my own head - I don’t know that it’s accurate - but I could and did mix and match when placing my order.
Before you commit, see if you can get samples from your trainer to see which your prefer.