Metalware , zippers, studs, buckles for repro ww2 jackets

[Cooper A-2]

Hi all,
just wanted to inquire who ( which ww2 flight jacket maker) uses the best accurate metalware, zipper , buckles, studs for their ww2 repro jackets?
Where can replacements be sourced?

 

[handymike]

Goodwear.
NOS parts can be purchased through MASH Japan.