4-step switch for 3-step fan Practical and flexible switch with 4 positions, designed for heating packages with 3-step fan and our cabin fans. Features: Modes : 4 positions (Off, Low, Medium, High) Compatibility : Fits heating packages with 3-step fan and our cabin fans Note : Not compatible with other heating packages without the use of a resistor to regulate the fan speed Connection : B: Plus (power supply) L: Low speed M: Medium speed H: High speed C: Active only when L, M or H is in position, can be used for additional functions such as turning on a light or starting AC. A versatile control that provides easy and precise control over the fan speed in your heating system.