Ann: Investor Update-4DS.AX, page-17

In laymens terms, 4DS are creating a different way of storing data onto chips.

The technical details aren't that important to understand, other than it's consistently been successful in trials and testing. I believe this kind of memory first came into existence around 2007, but it takes a long time to bring this kind of tech into affordable consumer technology, which should be very soon since it's nearly hit the 10 year mark.

The chips are significantly faster, with larger storage capability and potential to be significantly smaller.
From my understanding it will likely be scalable over time as well.