I2C LCD Display backpack, PCF8574 GPIO Extender

1. Size: 41.6mm (length) * 19.1mm (width) * 15.3mm (H)
2. Supply voltage: 2.5-6V
3.PCB Color: Black
4. Support I2C protocol
5. The power control with backlight can be set via jumpers backlight power supply is connected. Plug jumper to connect the backlight, then unplug the jumper is off the backlight power supply
6. The contrast can be adjusted by turning the blue potentiometer clockwise enhanced counterclockwise weakened. Potentiometer design on the front and the convenience of customers anytime, anywhere free adjustment
7. The module can cascade up to eight cascaded. / A1 / A2 modify the device address via short circuit A0. The default address is 0x27

And dont forget this can be used as regular GPIO expander.
here is schematic