Polaris #2879825 MTX SUB Enclosure only $275??

I was looking for sub enclosures to get rid of my box that sits in the bed and came across the polaris mtx enclosure w/sub directly from them. It seems to be marked half off since everywhere else on the internet places are charging double. IS this a price mistake since it comes with the sub? Also where in gods name does this go, I couldn’t find anything showing where it mounts.

http://www.polaris.com/en-us/rzr-sid…er/pid-2879825