2.13inch NFC-Powered e-Paper: Adopts novel passive NFC technology, No battery required, no more battery life ,Energy-Saving.APP is provided,Easy to use. Protective ABS Case,&Light Weight.Wireless NFC-Powered Display Refreshing, Passive NFC solution, No Battery Required, No messy wiring, stable operationHow it works. To refresh the display content, use a smart phone with NFC function, or an NFC reader, to the e-Paper for both wireless powering and data transfer. Refreshing Example: Refreshed By Smartphone, Comes With Android APP, As Easy As Swiping A Credit Card. Refreshed by ST25R3911B NFC Board.Power supply : Wireless . Grey scale: 2. Display color: Black / White. Refresh time:2s (data transfer time is not included). Dot pitch: 0.194x0.194. Display size: 49.70mmx21.75mm. Resolution:250x122. Outline dimension : 65.35mmx40.05mm. Viewing : 170degrees .Application examples. Suitable for Tags, asset/equipment Tags, shelf labels, conference name tags..., Resources & Services.Colour:WhiteMaterial:ABSPackage Contents:1 x 2.13 inch Passive NFC-Powered e-PaperOnly the above package content, other are not included.Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.