There are two dots. One is situated at 400,300 and the other at 399,300. In AoS, the actual point of accuracy for sights is in-between those two coordinates, therefore, by having two dots covering that point you can have a sight that attains maximum accuracy.
I have testing this myself (duh, it's the sight I use) and I can say this is a very effective sight. If you download and use this, you won't regret it.
Semi.png (Can also be used as an SMG sight!):
http://i.imgur.com/m0R5W.png
Tiki's version:
TIKI wrote:Didn't think it was worth making a whole thread for this but i've been using a modified version of your sight I made a little while ago
http://i.imgur.com/0gmEe.png
Here is an SMG Sight I made that was based on the M249 SAW by this gentlemen: http://ace-spades.com/forums/viewtopic.php?f=71&t=4848
This has the same accuracy as the sight above, but this one lines up your target making it easier to hit while moving, and while they're moving.
I use this, and I must same (somewhat shameless) it is brilliant.
Smg.png (Can also can be used as an Semi sight, though I wouldn't advise it.... Though this COULD be used as the shotgun.png):
http://imgur.com/bg6Pv