There are no markings or NSN numbers anywhere on it, as far as I could find. As you can see from the pictures of it draped over the LMTV bed, it's for a vehicle that is either not quite as tall, or slightly narrower, as the sides can't reach down far enough on an LMTV.
The zip open window in the front, as well as the two "drier vents" in the upper corners, are fairly distinctive.