Durable and Portable. The outer layer is made of thick TPR and with jel inside. 12 pcs lightweight stress relief squeeze balls in a plastic box for neat and storage. Great sensory toys, desk toys, novelty toys for teachers, officemate, classmates playing. Enough fidget balls for students to share in the classroom in the school. These anti-anxiety balls can also be used for wrist, hand therapy, and finger exercises. Recommend age 3+.