Fin screw and washer

[derbyshire surfer]

Hi,

I just received a new fin throughthe post today, it's 9' longboard fin but it came with no screw or washer. I'm sure you can get them from somewhere like Wlkos or somewhere but do they have to be like a particular material or anything?
I'm surfing Friday morning so wont be able to get any from a surf shop until after my first sesh.

Cheers