I have been throwing Magnets for many a years now and was wondering if anyone knew the history behind them. I have one disc that I bought back in 2004 and some others that I have bought recently. The one I bought in 2004 seems to have a different rim on it, but I can't tell if it's just because of wear and tear or if it is a different mold. Also I noticed that they have different amounts of chains on the stamp. Is there a reason for this?