THIS IS A LARGE COLLECTION OF HEAT SINKS FOR TRANSISTORS AND MOSFETS,LOTS OF DIFFERENT SIZE AND SHAPES. THESE ARE FOR TO-3 PACKAGES. THEY ARE DESIGNED FOR MEDIUM TO HIGH POWER DISSIPATION. TWO ARE IDENTICAL AND ARE MADE FROM HEAVY ALUMINUM AND DESIGNED FOR HIGH POWER DISSIPATION. ONE HAS TO-3 AND TO-220 CONNECTIONS.