My step mom gave me a set, nice box to keep them in. I've never juggled them, but when holding them all in one hand and move them, with out touching them together takes practice. Mine have a nice sound to them, the faster you move them the more sound. I think it's good to use them to help prevent carpel tunnel. You are working the tendons and muscles very well. I had a tendon problem in my left elbow, with exercises from a trainer and using those balls, made a difference for me. Carol In WI