T-00007B red anodized aluminum flange.
These may also be used on all RVs (except RV-12). The prepunched hole in the tank skin will need to be enlarged slightly(exact dimensions in photo).
These flanges will NOT fit the standard fuel tank supplied in Van's kits so they are really only suitable for use if you are building new tanks.
The rivet hole pattern in the T-00007B flange will match old production tank skins. Old production tank skins will have a 2.343 diameter hole for the cap where this cap requires a larger 2.625 diameter hole.