IDK why.
However, I personally would NOT want to buy "brakes" off of CL...
I would much prefer to go to a LBS for something that important. I mean if anything goes wrong, who do you take it up with...CL, the seller...That could get dicey!
Just call up Mikes Bikes and ask them about the most appropriate brakes for your bike. Then just go pick 'em up!
- Slim