I have two H&R sets and the bolts that come with he spacers have shallower heads, those are needed to mount the spacer to the hub. The original bolts hold the wheel to the spacer.

The part number is correct according to the H-R website in Germany. Seems you accidentally got a box with the wrong material in it.

These spacers are specifically made and approved for the e53. I have been running mine for year and nothing has ever broken or sheared.

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2003 4.4i black ext./black int./black headliner (kid's runabout)
2014 535d X-drive, M package, silver/black interior

Sold but not forgotten:
2009 E70 35d, black ext./black int./black headliner (sold 2021)
2006 4.8iS Le Mans blue/cream int./black headliner, SOLD in 2012 sadly...

Other hardware:
2015 Cayenne S (wife's new DD and definitely wroooommmmm)
2016 Tundra 1794 edition crew cab, luxo hauler
2005 Tundra crew cab, weekend hauler. Sold after 150k very happy miles.