This ball offers coordination training for handball, volleyball and football, and is also a toning exercise ball that will work on your arms, your legs and your pelvic mobility.
And it's easy to use. The ball is made of fairly thick, rubbery plastic and comes deflated (inflate using a needle pump), with a long piece of strong elastic cord and two toggles. The ball is formed with an eyelet aperture. Simply attach the elastic, as shown, using one toggle, and use the other to tie the trainer ball - either to yourself, as demonstrated here, or to anything solid enough to provide resistance.
And away you go! 20cm diameter. Comes deflated and boxed.
We have a choice of a simple needle pump here, or a more sophisticated version with flexible extension.