Fi'zi:k Tundra M3 K:ium Saddle. The Fi'zi:k Tundra M3 K:ium saddle is a superb choice for a mountain biker whose preferred riding is cross country training and racing. The robust and abrasion resistant Microtex cover can handle whatever punishment you dish out while at 200 grams the saddle won't weigh you down on the climbs. The Tundra M3's design is optimized for those who have a plenty of flexibility and as a result the saddle's shape is flat, narrow, and long. Additionally, the Wing Flex shell flexes downward where the inner thigh contacts the saddle, allowing more efficient pedaling and full range of motion.