Actually the Spin Matte Black 685 I had to buy is 670mm long. I was warned that these blades would be too aggressive and provide poor autorotating. Well, I am not a hardcore 3D flyer so long, but I try to learn. I do tic-tocks and some inverted manouvers. And I now always land in autorotation. No problems with the Spin Matte Black 685, and they are not too aggressive in any way. Actually, my E5 is much more agile in sideways flips, now running Zeal 570 blades, but where about the same with Rail 556's. Do you think my N7 would be more agile with Rail 696's?