BTFO 3pcs USB Fan Speed Adapter Controller, USB 5V to 12V 4 Pin PC Cooling Fan Adapter with Switch for Computer Cooling Fans (13.4 Inch/34cm)

["3-Pack Set: You get 3 pieces of USB 5V to 12V 4-pin fan speed adapters — perfect for projects that need multiple fan controllers. Enough for replacement, backup, or multi-fan setups.","Reliable Build Quality: Crafted from high-grade PE plastic and copper, these adapters deliver stable power output and consistent speed control. Built to last through regular use.","Easy Plug & Play Operation: No driver or software needed. Just plug the USB end into any power source or computer, connect the 4-pin to your fan, and use the switch and knob to adjust speed instantly.","Smart 5V to 12V Boosting: The adapter boosts a 5V USB input to a 12V output for standard 4-pin fans. Note: Only two wires are active — perfectly normal, as USB power requires only positive and negative lines.","Versatile Cooling Solution: Works great with CPU coolers, GPU fans, case fans, radiator fans, and other PC cooling components. An ideal low-power controller for managing internal temperatures."]