Those are userbars for different groups that you can join. Each group has their own different userbar.
When you join a group, you will get the userbar that they use under your avatar. Each group has their own requirements to join too.
Yea, @madara said it perfectly.
You personally can not put one on, only the group leader.
They are so sexy because a GFX god on the forum, Astro, makes them.