The Down Proof ticking is a woven material that is 50% cotton and 50% polyester fiber. It is a high thread count fabric designed to hold feathers so it provides a slow, smooth air release.
It also passes the Barrier Test for California's Technical Bulletin 117-2013.
The 4 denier fiber is a very fine, soft polyester fiber. It is hollow: which give s it more fill power, siliconized: which gives it a smooth feel, and has a conjugated crimp which provides more bounce.