Lost hex nut on 1/18 Roost

[Gvelayo]

I lost the hex nut on my roost. Anyone if you guys know what size they are? Is it #4 diameter with 40 threads per inch? Or is it in metric

 

[Heyitsme]

3mm locknut

 

[Gvelayo]

Thanks! I bought 10 pieces of those M3 hex locknut and washer as temporary fix. It works, thanks again.