truthfully I have no idea. SnoCross maybe? I know like your sled is Cross Country Racer(XCR), and an XC is a Cross Country, and a ZR is a Racer or a ZRT is a Racing Triple. I have no actual idea what SX stands for. They were just trying to keep it in line with their older product lines like the SX and SXR. I am gonna try and find out what it stands for now.