Det består endast delvis av polyuretan och resten är nåt som på engelska kallas split leather. Så här står det på wikipedia:
Bicast leather (also known as PU leather, bi-cast leather or bycast leather, sometimes described as split leather) is a material made with a split leather backing covered with a layer of polyurethane (hence the term "PU leather") that is applied to the surface and then embossed.
Splitleather is leather created from the fibrous part of the hide left once the top-grain of the rawhide
has been separated from the hide. During the splitting operation, the
top-grain and drop split are separated. The drop split can be further
split (thickness allowing) into a middle split and a flesh split. In
very thick hides, the middle split can be separated into multiple layers
until the thickness prevents further splitting. Split leather then has
an artificial layer applied to the surface of the split and is embossed
with a leather grain (bycast leather). Splits are also used to create suede.
The strongest suedes are usually made from grain splits (that have the
grain completely removed) or from the flesh split that has been shaved
to the correct thickness. Suede is "fuzzy" on both sides. Manufacturers
use a variety of techniques to make suede from full-grain. A reversed
suede is a grained leather that has been designed into the leather
article with the grain facing away from the visible surface. It is not
considered a true suede.