Turtleshell Helmet and Chinstraps

What is the Turtleshell supposed to be? Is it an uncovered PASGT helmet?

Also I've noticed that some helmets (such as the 'Bump' but also the Boonie) lack chinstraps compared to the PASGT and the High-Cut. Are there any plans to address this? I know this may be trivial but it feels rather out of place.

Stezz.

To me, it looks similar to the RBR F6 Mach 4, but I'm sure it's not simply because the ear cups do not angle outwards like they do on the mach 4. I believe it is based on a real helmet, but the name escapes me at the moment. Maybe a British Mk6 that's missing the extrusions around the ear?

The bump definitely needs a chin strap and could actually stand to be made into a larger size, but if the boonie is given a chin strap it certainly should be worn realistically rather than synced down tight which literally nobody does.

It looks a bit like a British Mk.6, but it's not quite right.

I don't mind the boonie not having a chin strap, it's small and not always used anyway. The Pro-Tec should have one, so that is a bit weird.

The Turtleshell helmet looks like the Israeli OR-201 Helmet without the Mitznefet helmet cover.