Only size 5, and size 4 are available for this. Although this should not be a major problem as this is for recreational play and practicing purpose, so kids are ok to play with this as well. In fact, the ball that will be given away to the developing countries will be used by the kids mostly. If you are buying this for an adult go for size 5, and if you are buying for kids or youth players then better go for size 4.
Adidas designs every World Cup ball, and on top of being a big seller for them, engineers at the company are constantly a little closer to the perfect ball, Goff says. The ideal soccer ball is a pimple-covered, perfect sphere, its surface just subtly textured enough to keep the airflow around the ball slightly turbulent. Unintuitive as this might sound, the ridges and pimples on the ball make it more aerodynamic, helping the ball to fly through the air more stably.
Soccer — or football as it's known around the world — is arguably the most loved sport on Earth. Although Americans still aren't as enamored of the sport as the rest of the world is, teams around the country are stealing hearts and minds, and Americans are getting into the game. For years, soccer has been a sport played by kids, college students, and ex-pats, but it's now being cheered in stadiums and watched on national TV. https://www.youtube.com/watch?v=DGp37du0xbQ