Fizik has taken its road-specific Arione saddle and tailored it for off-road duties, creating the Tundra.
It's been developed specifically for XC riding, and while it has the same large flat top and general shape of the Arione, it's a bit shorter and stubbier, as a result of the the front and rear bits being snipped off. There's extra padding in the nose for those steep on-the-nose climbs. Carbon braided rails keep the weight in the region of sub-200g.