10 packs TO-3P TO-247 Heatsink Kit, includes heatsink insulator/mounting kits + heatsink. The set includes 10 pcs Black Anodized Aluminium TO-3P Heatsink + Screw + Washer + Bushing and Insulator rubberized Silicone. It is used for heat dissipation and cooling of TO-3P power ICs