These Avar and Chinese helmets were all quite clever. First of all they all came from different places but they solved a similar problem. How do you keep a high hat on so troops can see each other’s helmets and unit symbols while making the helmet functional? Well, make the crown a hard and sloped metal surface that will deflect a sword strike from above and hold a flag or horse tail if necessary. The Huns adopted this helmet design from the Avar people, a nomadic equestrian society in Central Asia.
Avar Helmet Adopted By Huns From Avar People InCentral Asia.
6th Century Chinese War Helmet
Hunnish Avar Helmet
Imperial Guards Parade Uniform Helmet Qing Dynasty
Imperial Guard Helmet Qing Dynasty
Source; Wiki, Jordan Schnitzer Museum
As I see it, the 1st and the 3rd picture is of the same helmet, just from different angles, and with a different background.