What does the X4 mean in an PCIe Gen X4 NVME drive?

What does the X4 mean in an PCIe Gen X4 NVME drive? slot nvme Dual-Mode Slot Design Support both PCIe NVMe + SATA SSDs GIGABYTE Motherboards are built with dual slots With a PCIe NVMe + SATA dual-mode slot fire in the hole Yes, your notebook has a slot that supports NVMe SSD's HP only has the service manual for the older 15s-du0xxx model

slot fire in the hole Yes, your notebook has a slot that supports both SATA and NVMe SSD''s NVMe SSD's would provide faster readwrite

slot hacker 888 NVMe is designed specifically for SSDs with flash technology making it faster than AHCI drivers which was designed for common hard drives with spinning disk PCIe x4 slot with Lower impedance CONNECTIVITY Dual NVMe PCIe * Connectors