It's not safe!
Just in case some mommies don't know like I didn't since I'm going to be a new mommy.
Winter is coming and we want out babies to be warm but any accesory that doesn't with your carseat is NOT safe. Covers, pads, head rests, these blankies etc. If you want accesories you'll pay a little extra but you'll be at rest that that head rest was tested with your car seat and with those extra bucks are worth it.