text: WC 1966 in England.\n\nMost modern balls are stitched from 32 panels of waterproofed leather or plastic: 12 regular pentagons and 20 regular hexagons. The 32-panel configuration is similar to the polyhedron known as the truncated icosahedron, except that it is more spherical, because the faces bulge due to the pressure of the air inside. The first 32-panel ball was marketed by Select in the 1950s in the United States. This configuration became common throughout Continental Europe in the 1960s, and was publicised worldwide by the Adidas Telstar, the official ball of the 1970 World Cup.\n\nOlder balls were usually stitched from 18 oblong non-waterproof leather panels, similar to the design of modern volleyballs and Gaelic footballs, and laced to allow access to the internal air bladder. This configuration is still common, as are more novel ones, such as the 26-panel Mitre PRO 100T, and the 14-panel Adidas Teamgeist. There are also indoor footballs, which are made of one or two pieces of plastic. Often these have designs printed on them to resemble a stitched leather ball.