I'm really dissapointed in the fitment of the 10U for the Shoei Neotec. Why?
-Antenna is hard to place. When pushing it in the very small gap between outer and inner shell gets a few millimeters bigger and there is pressure on the outer shell. It's hardly noticable but it's there. For something that is protecting my head, I don't think it's good there is pressure from the innerside. I found your video when you put the anntenna in the shoei gt-air. But mine was not that easy at all.
-I found more reviews and pictures with the same problem: When the battery is placed you can't place the inner lining back nicely. The battery harness is coming to much inside the helmet and pushing the inner lining away. When you fasten the inner lining it's bulging out. See also what is described on this forum: https://ohioriders.net/index.php?/topic/108057-sena-10u-in-a-shoei-neotec/
Maybe Sena didn't consider/tested the different helmet sizes on the Neotec? I'm considering to send it back. Or you may have a solution/tip/trick to make it work. I find it a bit strange I can't find a video of fitment in a neotec on your site?
For your info: the neotec was bought a few weeks back and is a size M (57-58cm) And I'm sure I use a 10U for the neotec(that's what's on the box).