The HP 933576-001 is a multiplatform PCIe adapter for adding up to two M.2 NVMe SSDs to a workstation with a suitable PCI Express module slot.
Its PCIe x8 interface carries two Key M slots, bringing both M.2 storage connections onto one expansion card. The listed module lengths are 2242, 2260, 2280 and 22110, so check that a drive’s length is among the supported formats.
The HP Z8 G4 Workstation is listed as compatible. The HP parts catalog also identifies this part number as a dual M.2 SSD adapter. It is intended for workstation storage expansion where two M.2 NVMe drives are needed and the system has the appropriate slot. SSDs are not specified as included.