These are custom made, JC branded juggling balls. There are options available to buy these individually, or in pre-packaged sets of 3 make (make sure you select the option you want).
Made of artificial leather (polyurethane leather), filled with mix of ceramsite and plastic beads.
Each ball is aprroximately 2.75 inches (7cm) in diameter and weighs 110g.
Juggling can be a great past time to improve hand eye coordination as well as focus, and has been a hobby of James since his teenage years.