Why sheepskin?

Why sheepskin, why not synthetic material for slippers and boots?

Wool allows air to circulate freely between its fibres and you and it is this quality that allows the wicking away of moisture from the body to the outside air.
In winter, sheepskin is a natural insulator, trapping air between the fibres and capturing your body heat.
The protein wool fibres are hollow and can absorb up to 30% of their own dry weight which is then wicked away through the fibres to the outside air, whereas synthetic fibres can only absorb 3% of their own dry weight so the fibre, when wet, feels soggy to the skin. This is huge 30% difference between a wool and and a synthetic fibre.

The unique properties of sheepskin cannot be replicated by manufacturing technology. It is not possible to implant into a backing material between 4000 and 6000 fibres per square centimeter as can be found in sheepskin. It is the unique properties of each individual and independently aligned wool fibre that separate the genuine sheepskin from the many manufactured imitations.

Wool is soft, resilient, springy and very strong. It is also water and flame resistant and the lanolin in the wool acts as a natural moisturizer. Because wool allows a free flow of air it is very effective at removing odour as well.
The Merino breed of sheep is regarded as having the finest and softest wool of any sheep and it is this sheepskin that is sought to make the best slippers and boots.