1、Due to new passive near field communication technology, this 7.5‑inch electronic ink screen supports no need of built‑in battery power consumption without trouble of battery life. 2、Simple mobile APP operation, high‑quality ABS shell, beautiful and thin, new passive near field communication technology wireless transmission can be supported while no battery environmental protection and energy saving. 3、Built to strict quality control standards with simple installtion, E‑ink screen is improved for more durability. 4、To work stably, this e‑ink screen keeps new passive near field communication wireless brushing technology adopting passive near field communication scheme, which is no need for built‑in battery and no cumbersome wiring. 5、Smartphones or card readers with near field communication function can be near this product to wirelessly power and makes the display content refreshed while the display needs to be refreshd. 1 x E-Ink Display Item Type: E-ink screenPower Supply: Wireless power supplyGray Level: 2Display Color: Black and whiteRefreshing Time: 5s (not including data transmission time)Dot Pitch: 0.205 x 0.204Display Size: Approx. 163.2 x 97.92mm / 6.4 x 3.9inResolution: 800 x 480Viewing Angle: >170°