I've been meaning to post this for a while now.
I recently added this little jewel to my on-board tool stash with the Stelvio. It's a compact 17MM lug wrench intended for a Mercedes. It fits the Stelvio rear nuts perfectly and has just the correct amount of offset to allow proper access to the nuts.
I snagged mine off eBay and several were listed.
Mercedes part: 120 581 02 46