Glowstreak Night Time LED Fetch Ball, A Protected Inner Core That Contains An Advanced Motion Activated LED Module With Bright Red Or Color Changing Disc-O LED, Turns On With A Simple Bounce, Auto Shut Off Function After 10 Minutes Without A Bounce, Molded, Shockproof, Removable Polycarbonate Core Houses The LED Battery Module & Screws Securely Into Place Creating A Waterproof Seal, Same Size As A Tennis Ball, Invincible To Water Or Slobber, Floats, Great For The Dog Who Loves To Swim, The Unique Grooved Design On The Surface Creates A Bite Friendly Exterior That Is Easy To Pick Up, Uses Replaceable Batteries, Have Up To 35 Hours Of Playtime With The Glowstreak LED Ball.