Novel Passive NFC Technology, No Battery Required, No More Battery Life Trouble Passive NFC Solution, No Battery Required, No Messy Wiring To Refresh The Display Content, Use A Smart Phone With NFC Function, Or An NFC Reader, Close To The E-Paper, It'll Be Done In A Few Seconds Refreshed By Smartphone, Comes With Android APP Suitable For Price Tags, Asset/Equipment Tags, Shelf Labels, Conference Name Tags, Etc. No need for backlight, power off can keep the display content of the last screen for a long time It does not contain a power supply such as battery itself, which is suitable for application environments with limited power supply The displayed content can be customized and controlled by the user at any time through the smartphone, which is convenient and flexible POWER SUPPLY: Wireless DISPLAY COLOR: Black / White DOT PITCH: 0.217 x 0.217mm RESOLUTION: 264 x 176pixels VIEWING ANGLE: 170° REFRESH TIME: 6s (data transfer time is not included) DISPLAY SIZE: 57.29 x 38.19mm OUTLINE DIMENSION: 84.5 x 47.50mm color:Blue Material:PCB Package Contents: 2 x 2.7inch NFC-Powered e-Paper Module Only the above package content, other products are not included. Note: Light reflection 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.