Chain sizes

[gregvhen]

I went to ACE hardwar (which i hate but it was closest) to get a couple master links for my chain because i went up in the rear sprocket.  They didnt have 520, but they did have 50 which i know is same as 530, and they had some sizes that were like 2040 or 2060, stuff like that. Is one of those 20XX the same size as 520?