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.
The cheaper balls only have two polyester layers on their lining. Soccer ball bladders can be made from two different kinds of materials. They can either be latex or butyl. A soccer ball bladder is a component of a soccer ball and it is tasked in containing the air that is within the ball. It also contributes to its shape and the ball’s receptiveness on the field.
Latex bladders are one of the best materials when it comes to ball construction. However, with latex bladders, air won’t last as long as butyl bladders and will need more attention for proper inflation. Butyl-blend bladders hold in the air much better, but they are harder and less receptive in play. Mid-priced balls will usually have a mix of butyl and rubber. https://www.youtube.com/watch?v=c1SVcjYY6TE