Thanks for the replies and links so far. I have read those sources and that's how I learned about the 1050, 1680 and Cordura differences. But they are scarce sources for 2520 info. The D in my opinion is the abbreviation for denier, which as Gadget freak explained is a weight measure per yarn length. Nylon stockings for example are somewhere between 30 and 100d, ranging from very sheer (30) to practically opaque (100).

The main difference between ballistic and cordura is that one is more tear resistant (ballistic) and the other more abrasion resistant (cordura). In the real world these differences should be moot. Even 1680 should do. Also ballistic is shiny because it is one big smooth filament thread (a single strand at least for 1050d type) whereas cordura is soft because it is a textured yarn (multiple short fiber strands spun together not unlike cotton or wool). So the look and feel is different. In 1680 material they take 2x840 or 4x420 filaments and spin them together.

http://www.codi-inc.com/adv_1050d_Ballistic.pdf

The report in the link above is very informative if not necessarily from a neutral source. They say 1050d is the thickest fiber available. If that's true and if other available strengths include 840 and 2520, then I suppose that 2520 is 3x840, because a single 2520d yarn would probably not be very flexible anymore.

So basically, if that's the case, the question comes up whether between 2520d (3x840) and 1050d, the 1050d is still the winner as it is when compared to 1680d (2x840).

From reading their technical description, which I should have save because now their website is down, the Andiamo Bravo line was made out of (4!) yarns of 1050d. Whereas the Valoroso line was a weave of 3 1050d ballistic yarns in one direction and 2 1000d cordura yarns in the other direction, which would quite certainly place the Valoroso and Bravo materials at the top of the food chain so to say but also make them heavier, as can be seen in a comparison with other luggage brands.

Till