I just installed one of these covers on my truck a couple of weeks ago. I bought it from Cabelas for about $50. It came with the winter cover and a summer screen to keep bugs and rocks from hitting the radiator. It attaches with snaps but the snaps are not screwed to the grill. They are called Stik-a-Studs and are made by 3M. So far they have held up to rain, snow, sleet, and the powerwasher. I had one come un stuck from the grill but I dropped it on the ground when I was installing it so I am sure that is the reason it came off.
Hope this helps,
Mike