The first is this one:
http://www.gsfcarparts.com/603vg0700
£252.00.
The second is this one:
http://www.gsfcarparts.com/603vg0022
£23.40.
Now I can see from the info that the second one has completely different dimensions and it's solid rather than vented; it looks like it's not even suitable for the RS6. If that's true why do so many supplier sites list both when searching for discs for an RS6.
