This Coolus 'G' helmet is no longer available in the USA and I have the last one. 
Roman Army Brass Helmet Armor Coolus G Rhenus legionary auxiliary Augustan.  Type used by both the legionary and auxiliary forces in the Augustan age and the early Empire Civil Wars and Wars of Expansion.  Helmet comes with an arming cap for padded upper head comfort.  At this time, this is the only one of these types of helmet available in the US.