Russian balls are hollow juggling balls that are partly filled with sand, salt, silicone or other kinds of filling. The filling in the ball fall down to the bottom of the ball when you catch it, giving it a more solid feel. Russian balls are also is good for balancing, body rolls and other kind of contact juggling tricks because the filling sitting on the bottom of the ball makes it more stable, easy to balance.

The filling in the ball makes a big difference. Play Sil-x balls are parcially filled with food grade silicone, which gives the ball more stability when thrown, than with soild fill. Both types of Sil-x ball are the same, other than the Impossion having a transparent outer shell with colored silicone insdie, or the Sil-x with a colored outer shell with clear silicone inside. The both perform the same.

When you toss juggle a russain ball, the filling can cause the ball to wobble, from the filling staying on one side of the ball. The wobble effect is less with liquid silicone filled balls, like the sil-x ball and more pronounced with mirco-glass bead or other solid fillings. So there is a trade off between the amount of wobble and the increased stability for catching or rolling the ball. In general liquid filled balls are better for toss juggling (less wobble when thrown) and glass bead balls better for contact juggling (better balance).