I have Juniper account.
Thanks to Juniper, I could download ScreenOS.
http://www.juniper.net/support/downloads/screenos.html
As I mentioned above URL, NS-25, 204, 208 ... were not listed in.
So.. what I wondering idea is what is the latest ScreenOS version??
Now I have 5.2.0r3a.0 version.
maybe is it latest-version??