The NVMe SSDs like the 970 EVO or PRO will not work on this MacBook as this series uses an mSATA interface and not a PCIe interface like the 2013 and newer ones do.
I know that the SATA m.2 / mSATA SSD adapters with a SATA based SSD will work but is not recommended on here.
The options are to either get a Samsung or Toshiba original SSD. Problem is they are generally low in capacity like 128GB on this model so some may go the adapter method instead. I have not reported any major yet using SATA based SSD adapters. Only the ones I've seen problems with.
One downside of using third party SSDs is that TRIM is disabled by default which can cause performance problems over time.
The memory (RAM) is not replaceable on these MacBooks. From 2012 and later starting from the retinas they started soldering the memory chips onto the logic board making them not replaceable.
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