Very similar to the Ribchester helmet in the British Museum, made of bronze.
The stylised face of a young man with curly hair over the brow.
Over the top of the brow there is a diadem, decorated with flower forms.
References:
Anderson, M.L. (1990), "Cavalry sports mask" in Bothmer, D. von (Ed)., "Glories from the past. Ancient art from the Shelby White and Leon Levy Collection". Catalogue of an exhibition at the Metropolitan Museum of New York. (New York, 1990, 247)
Junkelmann, M. (1996), "Reiter wie Statuen aus Erz", p.49, Abb.99 & p.93/94