30pcs TO-220 Insulation Kit: Screws + Washers + Bushings and Insulator Rubber Silicone. Made of aluminum alloy, it has good heat dissipation effect. Material: Aluminum Alloy. Suitable for TO-220 Mosfet transistors, power ICs, can be used to cool regulators LM78XX, LM317, IRFXXX, TDAXX.
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