Power Bank Digital Display With Calling This Power Bank digital display not only can insert a menu picture in the both sides of device, but also can charge the customer's phone while they were enjoying delicious food. When you need service, and try to reach the waiter. just press the button of device, the waiter will come back to you. Description of Power Bank Digital Display: Product Feature of Power Bank Digital Display: ▪ Advertising picture inserted in both side of device ▪ With calling button to call waiters if customer wants service ▪ 20000mAh High capacity lithium polymer battery ▪ Charge both iPhone and Android mobile Phone ▪ The led digital display real-timely shows the remaining capacity. Product show: Certificates: Package Accessories: Deliver Way: Payment: FAQ: Color : only black color ?? Do you have another standard colors casing ?? >>>>Normal color is black. We could also do other colors, such as white, red. How many pieces of LEDs light inside ?? What is the watt per LEDs light ?? >>>> There is a led panel inside, not only LEDs, it is highlight. The light total power consumption is around 90~100mah. Device security : What is the size of wire ?? What is the material of wire ?? >>>> The length is 1 m. The thickness is 1.5 mm. The material is stainless steel.