00:10 there is a mechanism under the chin guard
04:38 as he swings the T.A., the close up frame show there are 3 layers of chin guard armor

Xenosynth wrote:http://imgur.com/W0St0OJ
Another bit of media that shows it is SRW W, just thought I'd upload it so people would have an image of it.

forgotten that it even appeared in SD Gundam G-Generation Overworld (2012) (PSP)

I just rewatched the Blue Frame OVA and the chin guard is a shutter mask!
Blue Frame didn't turn it to a mask but i found it, THREE layers of the shutter mask in chin guard mode.
exactly the same 3 layer armor as the line art, game appearance and the Gunpla Mod.

probably one of the reason that Bandai discontinued the mask gimmick, was that it was either hard or troublesome to make it into the scale of HG, NG and probably even MG as the Revise has even slimmer face.

didn't know peek-a-Boo style boxing was a real term. anyway, boxing stance with mask on did appear in the Gundam Generation of CE where Blue Frame equip the mask, fire a few shots with T.A. Gatling Mode, peek a boo stance and then rush onto the enemy exactly same as the lineart with Blue Frame charg...

The chin guard(?) of Blue frame Second L (not Revise) was able to flip up into a 'mask'. I first saw the 'mask' was many years ago while searching for Blue Frame videos in the 2005 PS2 game "Gundam Generation of CE", which Blue Frame Flip it's chin guard(?) into a 'mask' before charging on...