5Pcs TO-220 TO220 29.3w/m.k Ceramic Transistor Triac Thyristor Insulator Insulation Protection mica--1x14x20mm Provide excellent electrical insulation and great heat conductivity. Suitable for IC, MOS, transistors, Schottky, IGBT, etc.with TO-3Ppackages. Material: 97% alumina (AL 2O3) white