We bought the lighter version of these for general juggling practice and love them. I wanted something a little heavier to see if I could use my hobby as a little workout and found that yep they work your arms out which is great.and in addition they are so heavy they steady your juggling. If you lose control of the balls on occasion, the heavier ones help you juggle beautifully. The heavier ones are a lot of fun to juggle and learn new tricks with, keeps you from losing control as much as you do with the lighter versions.