The insulating material is plastic. This device allows adjustment of speed, heat, and brightness, and can be fully turned off. The controller features dual plug design and can be connected to a blanket. It is commonly used with fans, electric blankets, electric soldering irons, electric glue guns, small motors, incandescent lamps, blowers, and similar devices. Product type: Fan speed controller Power rating: 20-390W Voltage: 220V Frequency: 50Hz Note: When used with a fan at low speed settings, a noticeable current noise may occur. This is normal for external speed control devices in the market and does not affect performance. Please consider this before purchase if noise sensitivity is a concern. Warning: 1. Do not use with equipment exceeding 390W. 2. Not suitable for dimming LED or energy-saving lamps. Plug Type: US Plug, compatible with Canada, India, Mexico, Thailand, Taiwan, the Philippines, and other regions using US standard outlets. Color: Black Material: Plastic Package Contents: 1 x 220V Speed Control Switch Note: Other items shown are not included. Note: Lighting effects and display settings may cause slight color variations between the image and the actual item. Measurement tolerance: +/- 1-3 cm.