This is a 1:1 scale replica of the helmet mask worn by Mordred in the John Boorman movie, Excalibur, from 1981.
It is made by fibreglass, like the original, which was apparently lost some time after production. It had to be remade by armourer Terry English, and was united with the hero prop armour (only one set was made) and then auctioned by PropStore in 2014.
This wearable replica is 1 of 1 and was made in the U.S.