Each Yellow LED Ball Necklace features 7 yellow plastic LED Balls and 6 different light settings. With a click of the on/off button choose from a slow to fast flashing mode, super-fast flashing mode, blinking mode, the alternate ball flashing mode, all colors flashing and steady on. All of our Light Up Ball Necklaces come with (2) CR2032 batteries included and installed. Our Yellow LED Ball Necklace is perfect for any event with a yellow theme and they look great day and night! US Patent Number: 10,064,461