Connect this device with lamp or home appliance in a series connection, then rotate the knob for dimming, speed, voltage, temperature control. 
Applicable appliance: electric furnace, water heater, lamps, small motor, electric iron etc. 
Input voltage: 220V. 
Maximum power: 2000W. 
Adjustable voltage: 50-220V AC. 
Material: plastic, metal. 
Size: 4.8cm x 5.5cm x 2.7cm.