EFFECTS AND ADVANTAGESEach display box contains 3 types of balls of different size and density. In total it has 24 of them. Potentiate hands, fingers and forearm.COMPOSITIONPolyurethaneDIMENSIONSred: Low density. 70 mm diameter-24.04gr.yellow: Medium density. 17.39gr 63mm in diameter.green: High density. 13.68gr 75mm in diameter.MAINTENANCEThey can get wet, do not use bleach.