These are very nice for sensory stimulation. They are soft and stretchy, and the foam beads inside make soft noises when shaken or squished. I've used them personally and with my students, and my partner has used them with children in her therapy practice.
My only complaint is that the outside of the ball gets tacky and dull pretty quickly. The first one I used lost its sheen within 3 or 4 days of use as a stress ball. It sticks to surfaces and collects dirt and dust, but it hasn't broken down or left residue.