While most of Mavic's complete wheelsets come standard with UST tubeless compatibility, this is the only non-DH rim they do with a sealed UST spoke bed. The result is a relatively heavy rim for its width, and any tyre over 2.2/2.3in will tend to roll and flop under hard cornering.
The upside is that if you're not running fat tyres it's an impressively tough and sturdy hoop that's been hardtailed under our biggest riders without any warping.
Tubeless compatibility is obviously a great bonus if you're a low pressure fan or some other sort of innertubophobe. You're paying a fair bit of extra cash compared to standard Mavic rims, although they still look competitive when you put them up against DTs.