Features: Based on the raspberry pi 40Pin design, it can be directly inserted; for Raspberry pi 3B 4B hole position can also work for zero . Lead out all GPIO function pins- to test whether all pins- of raspberry pi 3B4B CM4- function normally As an extension version, this module-includes LED basic functions, which you can easily start with This is a simple extended version for those who are to raspberry pi. On board ADDA chip can read ADC signal and send DAC signal as sensor expansion version Specifications: Item: GPIO Test Expansion Board Size:approx 7x6x3.5CM/2.75x2.36x1.38in for:Raspberry pi Note: Due to the problems of lighting effects and shooting angles, there will be certain tolerances in the product, please understand. Please allow 0-2mm error due to manual measurment. Package includes: 1PC x Expansion Board 1Set x Screws