I've worked in aerospace for 20+ years and always crack up when I hear or read "aerospace grade". Most reels are machined from 6061 alloy which is used very little for structural aircraft components, 2024 and 7075 alloys are much more common when dealing with structural components especially those carrying any appreciable load. 6061's claim to fame is that it's fairly cheap, machines well, and is weldable. The shops I have worked in generally utilize it to fabricate tools to make other parts from. Nothing wrong with it for reel construction as I doubt reels ever see the kinds of loads and stresses that say a main wing spar see but IMHO "aerospace grade" is nothing but marketing hype, most aluminum alloys are used to some extent in aerospace but then again they're used alot of other places too.