For Sale: Slam that stem - low stack headset cover

Pre-2009 595 should be the same as my 585 and 464, 45mm diameter and 2mm deep. 2009 and later have the Headfit adjuster, not sure whether you can just bin that and use a normal bung type adjuster and plain cover.

Reading your post made me go back and question my eyes.
Mines the 2008 and I make it 46 diameter.