Review on 🔌 StarTech.com U.2 to PCIe Adapter - x4 PCIe - For 2.5" U.2 NVMe SSD - SFF-8639 PCIe Adapter - U.2 SSD - PCIe SSD - U.2 Drive (PEX4SFF8639) - Enhanced SEO by Chadwick Webster

I wanted to install this on a server that has physical clearance inside the case (for a full size card) but it only has one PCI -Low profile mount provide this. Based on the adapter pictures, I could just unscrew the included full-size bracket and attach the low-profile bracket (there are many network adapters, HCAs, etc.), but you can't. Both the spine spacing and hole spacing differ by 1-2mm - I'm not sure why they used something proprietary when the bracket screw hole layout is part of the PCI spec. I installed it anyway and resorted to a zip to secure it, but obviously less professionally. The card works perfectly - it is a passive device. Obviously the operating system must support U.2 drives.