slot m2 ✓ m2 slot means

slot m2
The specification identifies 12 key IDs on the module card Use ONLY when a double slot is being specified Label included inslot m2 SATA is just a complete wasted slot ; all slots should be dual NVMESATA capable, or

slot m2A slot that can do SATA will have the M key andor B key A slot that cannot do SATA will not have either the M or B key, but others instead

slot m2 Drives that use NVMe were introduced in 2013 to attach to the Peripheral Component Interconnect Express slot directly on a motherboard