All the descriptions I've found don't actually describe what it has that auto-adjusts. For example:
It says, "Floating bar adjusts to compensate for any gate sag"
And from my experience, it does in fact auto-adjust.
if you look at the related products below on your link, you will see similar latches where the bar is just a bent piece of metal with holes for mounting. i.e. a "fixed" latch. The "auto-adjust" has the box-like mount which allows some rotation/movement of the bar to engage the latch. Hence it "auto-adjusts" for some offset of the bar and latch.
Thanks. Sounds good.