Catit Senses 2.0 Motion-Activated Illuminated Circuit Balls (Set of 2) These Circuit balls light up enticingly as your cat plays with them! For use with the Catit Senses 2.0 Circuits Each ball includes two LR44 button cell batteries! Tip: re-insert the plastic card into the ball slot to elongate battery life Catit Senses 2.0 Motion-Activated Illuminated Circuit Balls, set of 2