Johntoy stress ball This stress ball is not like any other: it gives light! With the UV light that you can easily put in your stress ball and take it out again, you can even play in pitch darkness with this stress ball. The stress ball can take any shape you want. Guaranteed for hours of fun. Batteries are included. Specifications: Gender: junior Colour: white Material: rubber Batteries required: yes, LR41-AG3 Age: from 5 years