New OEM SSD - what is best backup/upgrade? (SD7SN3Q256G1002 - Zenbook UX305FA)

Bought Asus Zenbook UX305FA-USM1 with this SanDisk model 256 Gb M.2 SSD (search here the text “Storage Devices”; or “and M.2 SSD module” for pictured SSD).  This is my first experience with SSD and I am more than a little impressed!

But I worry about SSD and would perhaps like to have an imaged clone SSD ready at any time to replace the factory unit.  But a call to SanDisk phone tech support could not immediately recommend a replacement but instead suggested to contact Asus first for their recommendation.  So I’m coming here first for any suggestions.  A capacity of about 256 GB is sufficient for me, especially since the larger units seem out of my price range.

I’m still learning about the newer connections since the old days of IDE… but I believe this is “M.2”, not SATA III (?).  By the look of it, it is a 80mm in length.

I’ll probably have followup questions, so I’ll leave my question at that for now…  Any suggestions? … anyone with experience?

SanDisk does not sell a M.2 SSD in retail so there would not be a SanDisk SSD you can buy separately for your computer. Now that being said if your computer has a SATA 2.5" port or an MSATA port there are options from SanDisk but M.2 form factor is not sold in retail. 

Thanks for the info… although I am almost shocked to hear that “SanDisk does not sell a M.2 SSD in retail” .  This whole field of SSD drives is confusing to me with its different form factors, various standards and variety of manufacturers.

I just purchased a “2.5” sata to M.2 NGFF (B key SATA3) SSD adapter card with 9.5 mm thickness case" from China off an auction site (cheap) that shows M.2 style SSDs adapted to the more common 2.5" HDD interface.  Why would I do this?  Because I have an older laptop that sorely needs an SSD and I figure I could get a 256 GB M.2 SSD (not SanDisk evidently) and maybe try it in the laptop and also have it as a spare SDD available to replace the SanDisk in the Zenbook if it ever needed it.

Tell me I’m smart or… maybe I’m in for another shock (of failure)??