when the mobile is sending or receiving a signal, the mobile flashing sticker will flash with colorful light.when you cancel the bell of your mobile,flashing sticker can remind you when a signal is coming.its feature is without battery inside.only can be sticked mobile flashing sticker near the antenna of your mobile,can be used on all kinds of GSM mobile phones,if we print special logo and designs on mobile flashing sticker ,it will have excellent advertisting effect.its a great present for giving or gift for promotional prupose.