Cluster (polyester fiber) Sleeping Pillows: consist of high end polyester fibers spun into pellet size balls. There are thousands of indiviual clusters inside each pillow which are free to move around and rearrange inside the pillow. This increases the life of the pillow since no particular section will matt down, and it also immitates the feel of down. Our cluster fiber is not only one of the softest, but also one of the smallest clusters in the indutry, giving it a very smooth feel. The price is much lower than most retail discount outlets cause it comes to you direct from the manufacturer.