I ordered sensory tubes for my daughter and she loves them. The cylinder shape is very easy to grasp and explore with one hand. I have filled them with bells, objects of the same color, and pompoms covered in lemon extract her favorite smell. I don't recommend filling them with liquid as they tend to drip. I filled it with water and glitter as shown in the brochure and they all had a slow drip. Otherwise this is a great product!