I am an I/O expansion module based on I2C interface control, which can expand up to 16 I/O ports and supports the simultaneous use of up to 8 expansion modules for a total of 128 I/O ports. Compatible with 3.3V and 5V logic levels, it requires only 2 signal lines to expand 16 I/O ports. The I2C communication address is configurable by shorting A0, A1, or A2 solder joints. Offers two interface types: PH2.0 terminal and solder pad, supporting daisy-chaining of multiple I2C modules. Built-in level shifting circuitry allows compatibility with both 3.3V and 5V operating voltages. Working voltage: 5V / 3.3V Control interface: I2C Product dimensions: 38mm x 23mm Via diameter: 2.0mm Color: As shown Material: PCB Due to different product batches, appearance may vary slightly, but this does not affect functionality. Package includes: 1 x Expansion module, 1 x Cable Contents are limited to the items listed above; other accessories are not included. Note: Lighting and display differences may cause slight color variations between the image and the actual item. Measurement tolerance: +/- 1-3 cm.