A sole for footwear, especially sports footwear, has a lower layer provided with transverse ribs and an upper shock-absorbing layer. The lower layer may be of natural rubber of Shore hardness from 55 to 60 and the upper layer of lower-density natural or synthetic rubber of Shore hardness about 40....http://www.google.co.uk/patents/US4130947?utm_source=gb-gplus-sharePatent US4130947 - Sole for footwear, especially sports footwear
