Black SN750 NVMe WDS250G3X0C 250GB is an SSD type hard drive which can fit 250 GB of data. This model has an M.2 form factor.
From Amazon
WD_BLACK SN750 250GB M.2 2280 PCIe Gen3 NVMe Gaming SSD up to 3100 MB/s read speed
Western Digital
WD_BLACK SN750 NVMe SSD 250GB, Without Heatsink
EE Store
WD 250GB Black SNT750 NVMe M.2 2280 PCIE Gen3 SSD
Novatech
WD Black SN750 250GB NVME M.2 3D Performance Solid State Drive/SSD