M.2 - I'm struggling to keep up.

[Diggs]

After doing some tooling around on it looks like there is no such thing as a B key NVMe SSD. But I did find that the B + M key is supposed to work in either a B slot or a M slot.

I guess I had it wrong. It had a 32 GB B&M key NVMe Optane and I was looking to replace it with a 250 GB B&M key NVMe but cannot find one. (I thought B-key had both slots but not.) Like my post said, I'm really struggling to understand the M.2 variations.