Tunit or resin rubber outsoles were developed in the early 1950´s with the purpose to imitate leather. With a base of vulcanized rubber made with synthetic SBR rubber reinforced with styrene resin. Normally it´s produced in sheets and cut into shape.

• Leather like
• Flexible
• Low Cost

It´s generally used for the leather look, abrasion resistance and flexibility. The fact that it generally costs less than leather makes it a popular material for outsoles.

This type of outsole is often reffered to as "German" outsole in China.

References

https://www.onehugestep.com/pages/faqs

https://howtoshoes.blogspot.se/2014/05/basic-of-shoes-bottom-parts.html

https://en.wikipedia.org/wiki/Styrene-butadiene