I have really come to loathe full-moon discs. The pop-on ones are terrible.
I lost one a couple months back during a trip to PA ... so I ordered a replacement from Hubcap Mike's. It came on Thursday ... dented in. I pushed it back out and hammered out most of the ripples.
Put it on the car and the same one popped off some time today. I am through with these things. What a wretched design.
