Eduardo, I don't think Chris in the UK can sell us parts over here any more. I was able to get a dealer here in Texas to order a European part number (one that had never been sold in the US), they had to submit a request and MB had to release the PN for nafta sales. Took an extra week or two but they got it done. Try to get your dealer to run a availability on those windows.
I was able to get genuinemercedesparts.com to order a European accessory as well , just total list price and gnarly lead time. Chris is bound by franchising rules, he can sell in the uk but then you have VAT tax and have to ship them to a third party in the UK and then ship em to US of A.
Those windows are awesome though!!
2013 KTM 500exc