SanDisk SSD x400 M.2 2280 -- SATA or PCIe?

I’m trying to replace the 256 MB x400 M.2 SSD in my son’s laptop with a larger capacity SSD.  Can anyonetell me whether the x400 is SATA or PCIe?  

Thanks for your help!

the x400 is SATA

https://www.sandisk.com/content/dam/sandisk-main/en_us/assets/resources/enterprise/data-sheets/X400-datasheet-v1-1.pdf

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