Super lovely colorful shining pendants with 3 kinds of different strings,made with plastic and electronic module.TM00057 is on-off switch with 3pcs AG3 batteries,only one flash mode-constant on,you can choose different lights to match your pendants.TM00053 is push button switch with 2pcs CR1620 batteries,3 flash mode-fast flash,slow flash,constant on,TM00056 is fiber optic necklace with 2pcs CR2016 batteries,3 flash mode-fast flash,slow flash,constant on.Customized logo can be printed on the swithc.We are welcom OEM order,just offer us picture we will make custom shape for you necklace.