Crazy Critters LED Dog Leash and Collar Set Walk safely in the dark! Each Crazy Critters LED Dog Leash and Collar set is made of 100% new, sturdy nylon and satin blend. Normal battery life is 4-5 monthes (based on 60 hours of steady light or 100 hours of flashing light. Each collar and leash light up in 3 different modes: fast blink, slow blink, and solid. Battery is replacable 2PCS CR2032 button battery