This happens a lot with flash in general, mostly because those who manufacture the end user product don't usually make the NAND (or don't always use their own).

This happens a lot with flash in general, mostly because those who manufacture the end user product don't usually make the NAND (or don't always use their own). I had the issue with "high end" USB sticks a while back during a review. The speeds given are completely irrelevant and always based on best case scenarios. And while a few manufacturers stick to the same formula for controller + NAND for the life of the product (say Sandisk), others just don't care and will silently switch both the controller and NAND with 0 indication on packaging (no rev., no nothing). On SSDs I can't remember seeing that though, but then again, this is Western Digital we're talking about. A company best known for, let's say, being a very late entrant to the SSD market. Edit : At least they (kinda) owned up to it after being caught, quoting the updated article : "For greater transparency going forward, if we make a change to an existing internal SSD, we commit to introducing a new model number whenever any related published specifications are impacted,"