bolts for ris rail

[zerowatt]

Ive just brought a foregrip so need to attach a ris rail to my m4 ive got the ris rail but dont know the size bolt I need to attach it

 

[jcheeseright]

how long is a piece of string?

on a similar note, I have just bought some new air fresheners for my car, what size tyres should I buy?

 

[Lozart]

Ive just brought a foregrip so need to attach a ris rail to my m4 ive got the ris rail but dont know the size bolt I need to attach it

Click to shrink...

In other news, I assume the forgrip is second hand? Can you take some pictures so we cxan get an idea of what you've bought?