1. 4.2inch Passive NFC-Powered e-Paper,Adopts novel passive NFC technology,Wireless Power & Data. No battery required, no more battery life trouble,Energy-Saving. APP is provided,Easy to use.Protective ABS Case,Nice&Light Weight.2. Wireless NFC-Powered Display Refreshing. No messy wiring, stable operation, fast refreshing3. How it works: To refresh the display content,use a smart phone with NFC function, or an NFC reader,then close to the e-Paper compatible with both wireless powering and data fer.4.Supported smart phones: Most Android phones with NFC function are supported,some tested and confirmed devices are listed above in the picture (include but not limited to)5.Application examples: Suitable compatible with price Tags, asset/equipment Tags, shelf labels, conference name tags,etc. Specifications:Power supply:WirelessGrey scale:2Display color:Black / WhiteRefresh time :4s (data fer time is not included)Dot pitch:0.212 x 0.212Display size:84.8mm x 63.6mmResolution :400x300Outline dimension :105.1mmx94.1mmViewing angle : 170°Material: ABScolour: White Package Contents:1 x 4.2 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.