They are six balls made of durable rubber. The material is the same for all six but they differ in color, size and relief. The manufacturer states that they are suitable for children from 0-3 years.

It was a toy that suited his development exactly

I tried them out with my grandson, who is over a year and a half old. His interest was immediately aroused. He abandoned his other toys for them. He enjoyed taking them out of the box one by one, grabbing them, feeling them and putting them in his mouth. Then letting them roll away or throwing them, looking for them again and putting them back in the box or in something else. Because the balls are soft, can be pressed a little and have a relief on the outside, he could easily grab them. The rubber itself also feels a bit rough. Although that did not quite work, he also tried to put them in the right compartment in the box. It remained his favorite toy for that day and the next day. His game was mainly putting the balls in something, taking them out again, letting them roll around the room, looking for them again and putting them in something else. And in the meantime he regularly put them in his mouth. It was a toy that suited his development exactly. He likes the balls because they look different and feel different. Because he can walk quite well, he could easily chase the balls when they rolled away. That way he was busy with them all the time.

Because the box says they are suitable for ages 0-3, I also looked at what my granddaughter – just under 4 months old – did with them.
She was in the same room but not interested. She couldn't do much with it either. She could only look at it, but she couldn't grab it or chase it when it rolled away. I think the balls are best suited if you can grab it well. And even more fun if you can move on the floor by crawling, walking or in some other way.

And what did I think?

Seeing the balls in the box immediately tempted me to pick them up, move them between my hands and feel them. I think mainly to feel the difference in relief. You can see that they differ in that, but by grabbing them and moving your thumb and fingers over the surface you feel the differences better. The material of the balls feels nice. And because they can be pressed in a little, it tempted me to roll them between my hands. It gave a nice feeling to have them in my hands. I didn't put them in my mouth, but when I was thinking about writing this piece, I did notice that I liked rolling them over my face, especially along the line of my lower jaw. Rolling the balls between my hands and over my jaw ensured that I wasn't distracted when I stopped typing. I clearly had a preference for the two larger balls - possibly also because of the size of my hands.
As an experiment I also rolled the balls over my legs and arms but that had much less effect for me. Automatically I picked up the larger red ball again and rolled it between my hands and over my face. That may also have to do with the size of the balls and my body, and it has a different effect on young children.

Conclusion:

The six sensory balls are best suited for children from 9 months to about three years. Because they can be pressed, have relief and feel somewhat rough, they are easy for small hands to grasp. They are especially fun if you can chase the balls. The balls encourage movement such as crawling, walking or in whatever way. They are interesting because of their differences in shape, size, relief and colour. The balls also feel pleasant. They encourage exploration of their various possibilities. The balls are a sophisticated product for this age group that guarantees a lot of fun playing. We will just have to accept the somewhat higher price.

With older children and even adults, the balls can also be used in other ways. In that case, the focus will be less on research behavior, but it can be used as a kind of touch memory, for example by putting a ball in a demolition, letting the child feel the ball without looking and letting them point to the box to see which ball was put in the demolition. Touch memory. And possibly also as a tool to be less distracted. concentration and Something to feel.