The scaling option: the Board contains 3 x jumper and allows you to store up to 8 of these devices on a single IIC bus. Overall, has this board 8 input / output pins. Therefore, if we plug in 8 of these modules for yourself, then we can control up to 64 pins. Pins can switch to zero. The logical ones they supply an extremely small current, and this solution no other circuits is not recommended.
The Datasheet of the main IC:
1pcs PCF8574 I/O Expander I2C-Bus Expansion Board