Help with model

I wanna know if my mbp 13" mid 10 is a model 7.1. My serial number (found under "about this computer") is WQ0164TSATM and I also found some other number 12D78. But none of them correspond to anything in this article. So, how do I find out if it is a 7.1 model or not?

The reason I'm asking is because of the mini displayport. I've seen a lot of people ask about wether it will work with sound through hdmi to their hdtv or not. And I know that 7.1 support this.

Thx!