Nite Ize GlowStreak LED Ball/SpotLit Combo Disc-O. It is motion activated and also has an auto shut-off function after ten minutes giving you time to find it if your dog has gotten distracted and to optimize the replaceable long-lasting batteries. Diameter is the same size as a tennis ball and invincible to water or slobber this tough little ball is ideal for playing fetch with the ball-loving dog who wants to take it for a swim or play fetch for hours into the night. This ball is not intended as a chew toy nor is it intended for pets under 12 months old. It is meant for supervised use only and for enjoying playing fetch with your dog. Please tighten the battery cap securely in place using a flathead screwdriver and check the tightness regularly. Nite Ize SpotLit LED is a great mini-beacon whenever you need a little help in the dark. Set in a lightweight stainless steel carabiner it attaches quickly and securely to key rings jackets - just about anything with a hook or zipper. Its long-lasting LED provides an ambient glow bright enough for everything from reading fine print to finding your car door keyhole. Attached to things like tent lines and camping gear it provides instant location of hazards and necessities; attached to your person (jacket backpack running belt) it tells other people where you are when they might not otherwise see you. Choose from two modes: press once for steady glow twice for continuous flash. Water-resistant long-life replaceable batteries included. Specifications for Nite Ize GlowStreak LED Ball with SpotLit LED Collar Light: Manufacturer: Nite Ize Color: Disc-O Weight: 0.6 oz Fabric/Material: Rubber Features of Nite Ize GlowStreak LED Ball with SpotLit LED Collar Light: Durable LED Ball for nighttime play Motion activated Auto shut-off after 10 minutes of inactivity Durable rubber construction Waterproof - it floats Run time: 35 hours 2 replaceable CR2032 batteries included Diameter: 2.5" 63mm Push on/off Glows and flashes Water resistant Run time: Glow: 20 hours Flash: 25 hours Easily replaceable 2x 2016 batteries included Dimensions: 2.12" x 1.28" x 0.85" 53.92mm x 32.70mm x 21.78mm Nite Ize GSBC-07-R7: GlowStreak LED Ball/SpotLit Combo Disc-O