Waveshare All-In-One Aluminum Alloy Cooling Fan for Raspberry Pi 4B, PWM Speed Adjustment

A fan that only runs at full speed or not at all is either noisier than it needs to be during light loads or risks falling behind during a heavy one - PWM speed control fixes that by letting the fan's speed scale with how much cooling the board actually needs at any given moment. Built specifically for the Pi 4B's mounting layout and in an aluminum alloy construction that itself contributes some passive heat dissipation alongside the fan's active airflow, this is a complete, dedicated-fit cooling solution rather than a generic fan bolted on with improvised brackets.