This is a costume worn by Dev Patel in THE GREEN KNIGHT directed by David Lowery.
This costume can be seen at the beginning of the film in King Arthur's roundtable throne room where Gawain (Dev Patel) accepts the challenge by The Green Knight and beheads him.
This costume is custom made by the production and has "Gawain # 2" written inside.
Interesting fact, costume designer Malgosia Turzanska had to negotiate some quirks of this particular production, in particular, sourcing cruelty-free replacements for fur and leather due to the director's veganism. So most of the costumes, including this one, are completely vegan.
The craftsmanship, attention to detail and materials are absolutely superb on this costume.
Thanks for looking!