The enclosure supports M.2 form factors including M.2 2280, which matches the WD SN850X size. However, the WD SN850X with heatsink has a thickness of approximately 8.8 mm, while typical M.2 enclosures, including this one, are designed for standard M.2 SSD thickness without heatsinks. Therefore, the WD SN850X with heatsink will not fit inside this enclosure due to the heatsink's added height. The enclosure is compatible with M.2 SSDs without heatsinks only.