The coat of the yak is composed of three different types of Fiber that vary greatly in appearance and characteristics. The quantity of fiber produced by one yak is dependent on factors such as sex,Website:http://www.xc-cashmere.com, age and breed of the yak, and the proportions of the different layers vary throughout the different seasons.The coarse: Mostly used by nomads in tent making, this fiber has a size range of 79-90 microns forming the outer coat of long hair that characterizes the appearance of the yak.The mid-type: With a diameter size between 20-50 microns, this fiber is naturally strong but not stronger than the outer layers to make ropes and tents and not as fine as the down fiber for the textile industry.The down fiber: This is the finest fiber (16-20 microns) and is generally shed by the animal during late spring/early summer period. Therefore, this fine layer needs to be harvested before it is shed in the summer season. Down fiber, and fewer sweat glands, are two examples of how yaks have adapted to survive extreme cold temperatures (sometimes as low as -50 ?C, or -58 ?F) and altitudes well above 3000m