Why only 4.2” display has buttons and not others?
- Because the refresh rate is closely related to built-in color. More built-in color, the screen needs more time to respond. It’s not possible to use button to immediate respond.
- 4.2” display has 4 buttons for interactive function, so it needs a faster refresh rate to change the screen content. So it doesn’t have any color built-in, only black & white.
- For 2.9/7.5”, they have red/yellow color built-in.