Galea padding?

[Tarbicus]

I use the bog standard liner that comes with the Deepeeka helms, a medieval padded linen arming cap that covers the neck and cheeks (excellent for added stability if the ties are threaded through the cheek piece tie rings), a phrygian cap, and a wool Dura cap. Different helmets seem to be better with different caps. Yet to find the right kind of sponge as described by Aristotle.
http://www.romanarmy.com/rat/viewtopic.php?t=15354