Camloc or Skybolt fasteners

[my53cad]

I have an RV9A with the top cowl using I think Camloc Stainless Steel Phillips head fasteners at the firewall. Any ideas on what size they might be or how to measure for size. I am driving myself crazy trying to order spares because I know I will lose one eventually!!

 

[Freemasm]

Don't know what you have. Look closely (it is small) at the head of the fastener. Depends on the manufacturer but good chance there's a dash number (length) on it. Take a digital pic and zoom. If nothing there, measure.