Features: Brand new and high quality This is a thin heat sink, equipped with 3510 quiet cooling fan, suitable for rpi 4, which provides better cooling effect through passive cooling and protects rpi. In addition, it provides faster cooling by active cooling using PWM fans. The speed of the fan can be easily controlled by using the Pythons script provided, which is perfectly for RPiOS. Other system need to manually write Pythons or C codes to drive the fan speed through PWM. It is very easy to install, and provides a good contact surfaces betweenonboards components and the radiator using the attached thermal pads. A good contact surfaces is provided between the onboards assembly and the radiator through the heat conducting pad. Specifications: Material:Aluminum Alloy Size:Approx.6.5x4.9cm/2.56x4.93inch Package Includes: 1 Set Aluminum Heatsink note: 1.Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item.