[Low-Tech] Which pieces of armor have neck gaps?

[Ulzgoroth]

LT101 gives us, among other things, neck armor gaps targeted at -8.

But I'm not sure when and how they work.

Just targeting the neck is at -5, so this has to be working around some sort of armor. But which armor? By a literal reading, any non-flexible neck protection, but that seems hard to believe.

A Turret is a big, bulky, more than neck-covering tube with nothing like articulation. Does it really have gaps?

Does a Bevor have gaps? The pictures I find are of big solid metal plates that don't seem like they'd have any such vulnerability.

Scale Aventail and (segmented plate) Lobsterback?

Probably any Greathelm that isn't fixed to the torso armor has neck gaps?

I assume a Gorget is the perfect example of armor with neck gaps...