I've got a couple of pairs of the 520's. 100% satisfied.
According to Jenson's listings, there is a 20gram difference between the two.Price is about $40 and $90 respectively. Is that weight savings worth an additional $50? Not for me.
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"I tell you, We are here on earth to fart around, and don't let anybody tell you any different." - Kurt Vonnegut jr.