Many sizes screw posts
1) Iron material,nickel plated,it can last for a long time.
2) Chicago Rivets for ring mechanism,notebook,boardclips,etc.
we have the sizes as the picture and page.
******For ring mechanism
As common,if there is no trigger/booster,3mm screws is ok.If there is a trigger/booster,8mm or 10mm screws will be ok