4 Pack 1.4 inch Ultra Soft Sponge Balls - Red by Ronjo

The basic sponge ball effect is beautifully simple:
A magician places one soft sponge ball in their own hand and another in the spectator’s hand. With a magical gesture, the ball in the magician’s hand vanishes. When the spectator opens their hand, they discover both balls have impossibly gathered together in their palm.
That’s the core effect — objects appearing, disappearing, multiplying, and traveling — all happening right in the spectator’s closed hand, which is why sponge ball magic hits so hard.