1. 0.91 Inch OLED Display---This is a 40pin Raspberry Pi HAT type expansion board, which provides a 0.91 inch display screen connected to the I2C pin; The display information can be presented as it is without customization through the program. 2. Speed Adjustable Fan---It provides an ultra-thin 4007 silent fan to provide heat dissipation support. 3. Programmable LED Indicator---There are 4 LED lights on the back of the board. You can control the lighting mode of the LED lights through simple programming. 4. GPIO expandable interface---The previous HAT board design is used. The 40Pin GPIO can still be easily accessed by users. The fixing method avoids the risk of short circuit caused by metal parts and provides a good appearance design. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.