1. 4.2inch Passive NFC-Powered e-Paper,Adopts novel passive NFC technology,Wireless Power & Data. No battery required, no more battery life ,Energy-Saving. APP is provided,Easy to use.Protective ABS Case,&Light Weight. 2. Wireless NFC-Powered Display Refreshing. No messy wiring, stable operation, fast refreshing 3. How it works: To refresh the display content,use a smart phone with NFC function, or an NFC reader,then it to the e-Paper for both wireless powering and data transfer. 4.Supported smart phones: Most Android phones with NFC function are supported,some tested and confirmed devices are listed above in the picture (include not limited to) 5.Application examples: Suitable for Tags, asset/equipment Tags, shelf labels, conference name tags,etc. Specifications: Power supply:Wireless Grey scale:2 Display color:Black / White Refresh time :4s (data transfer time is not included) Dot pitch:0.212 x 0.212 Display size:84.8mm x 63.6mm Resolution :400x300 Outline dimension :105.1mmx94.1mm Viewing angle : 170 Material: ABS colour: 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.