Monkey fist balls are a good idea for replacement balls for most any routine that uses such things. I use them for a cups routine that I perform on stage at LEAST a half dozen times each week.

This particular set is on the small side - about 3/4" in total and rather light. I think that they may be wrapped around cork centers, but I didn't take them apart to make sure.

They would work well for smaller sized cups (they will easily nest all three balls in any standard cup) or any application where the weight might become an issue. They might not be the best for outdoor use as a strong wind will blow them across your performance table.

On the good side they stay where they fall without rolling all over the place due to the monkey fist design, and they handle well due to the covering. They are easy to palm and manipulate.

My use needed something bigger and with more "heft", so these didn't quite fit the bill. They are okay, and will last, but not an ultra high quality product. YMMV.

These are okay for Cups and Balls but they aren't the most beautiful props really. I've brought some slightly for expensive balls but they look and feel better than these do.