Plastic. It's some kind of see through plastic with a reflective surface. You have no idea how hard to breathe it is in that helmet, specifically indoors where there is no fresh air. I bought it online after Party city got sold out. (waited too long) Although theirs was online only too.
Funnily enough, the dagger accessory was a separate item. And it didnt even stay on the leg. Not only was there not enough Velcro to tighten it enough, but it kept sliding down due to the smooth material of the suit. So I had to attach a fabric strip to my belt to hold it there. The belt is also customized with a belt I had around, since the one attached to the costume was balls and just hung there.
And good thing I had my own boots, since the boot covers were about as [parasitic bomb] as you wold expect boot covers to be.