My concern is what will happen when someone points out that the non manufacturer addition of the C-flap invalidates the NOCSAE approval of the helmet. And/or the addition of the c-flap by the end user invalidates any expressed warranty from the manufacturer.
In reading some of the reviews of the Markwort C-flap sold in many big sporting goods stores, difficulty in attaching the c-flap lead some to have to drill multiple holes in the helmet shell. And that the C-flaps are not "one size fits all".........leading to some helmet types not being able to fit an aftermarket c-flap at all.....
I can see manufacturers offerings for next season may include helmets with a integral c-flap molded into the shell or factory attached to pass NOCSAE standards.