I prefer the 2" sponge balls, but these are great for smaller hands, for clandestinely loading more sponge balls into someone's hands than you can get with the 2" ones, or for carrying around in your pockets if you're wearing jeans or something. Excellent quality, but choose a size ball that suits your performance needs.
I like the black ones because the dye tends to be more even across the surface of the ball and mor consistent from ball to ball. Also, while it shows lint real well, the black color hides the dirt that can accumulate on the sponge balls over time and much use. The lighter colors tend to show the dingy stuff sooner.

Good for practice and performance.

I've been using them on a daily basis at the place where I perform and the color is still there, they dont fade away! I do recommend them :)