2.9 Inch NFC-Powered e-Paper.Adopts novel passive NFC technology. No battery required, no more battery life trouble. APP is provided,Easy to use. Protective ABS Case,Nice & Light Weight. Wireless NFC-Powered Display Refreshing,Passive NFC solution, No Battery Required, No messy wiring, stable operation How it works: To refresh the display content, use a smart phone with NFC function, or an NFC reader, close to the e-Paper for both wireless powering and data fer. 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 fer time is not included). Dot pitch : 0.138x0.138 . Display size: 66.89mmx29.05mm. Resolution : 296x128 . Outline dimension : 87.5mmx47.7mm. Viewing angle : 170°. Application examples: Suitable for price Tags, asset/equipment Tags, shelf labels, conference name tags Resources & . size: 87.5mm x 47.7mm Material: ABS colour: White Package Contents: 1 x 2.9 inch Passive NFC-Powered e-Paper Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.