I have stumbled upon this helmet by change, and cant decide whether it is authentic or not. It is supposedly dated to the 8-9th century:https://www.the-saleroom.com/en-us/auction-catalogues/timeline-auctions-limited/catalogue-id-srtime10031/lot-be327cb7-d051-4ec1-b1b6-a45401840c91


The thing I find odd about this helmet is the number of rivets that connect the bands to the rim. Each end is secured to the rim with 3 rivets, instead of the usual 2. The other thing that puzzles me are the ridges of each band. These would certainly serve to strengthen the helmet, but they are present on only a few of the spangen/bandhelms that I am aware of, namely the burgh castle helmet, and the gnezdovo 1 type helmets.

So what do you think, authentic or not?